1
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Habibi P, Dey P, Vlugt TJH, Moultos OA. Effect of dissolved KOH and NaCl on the solubility of water in hydrogen: A Monte Carlo simulation study. J Chem Phys 2024; 161:054304. [PMID: 39087538 DOI: 10.1063/5.0221004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Accepted: 07/15/2024] [Indexed: 08/02/2024] Open
Abstract
Vapor-Liquid Equilibria (VLE) of hydrogen (H2) and aqueous electrolyte (KOH and NaCl) solutions are central to numerous industrial applications such as alkaline electrolysis and underground hydrogen storage. Continuous fractional component Monte Carlo simulations are performed to compute the VLE of H2 and aqueous electrolyte solutions at 298-423 K, 10-400 bar, 0-8 mol KOH/kg water, and 0-6 mol NaCl/kg water. The densities and activities of water in aqueous KOH and NaCl solutions are accurately modeled (within 2% deviation from experiments) using the non-polarizable Madrid-2019 Na+/Cl- ion force fields for NaCl and the Madrid-Transport K+ and Delft Force Field of OH- for KOH, combined with the TIP4P/2005 water force field. A free energy correction (independent of pressure, salt type, and salt molality) is applied to the computed infinite dilution excess chemical potentials of H2 and water, resulting in accurate predictions (within 5% of experiments) for the solubilities of H2 in water and the saturated vapor pressures of water for a temperature range of 298-363 K. The compositions of water and H2 are computed using an iterative scheme from the liquid phase excess chemical potentials and densities, in which the gas phase fugacities are computed using the GERG-2008 equation of state. For the first time, the VLE of H2 and aqueous KOH/NaCl systems are accurately captured with respect to experiments (i.e., for both the liquid and gas phase compositions) without compromising the liquid phase properties or performing any refitting of force fields.
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Affiliation(s)
- Parsa Habibi
- Engineering Thermodynamics, Process and Energy Department, Faculty of Mechanical Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, The Netherlands
- Department of Materials Science and Engineering, Faculty of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands
| | - Poulumi Dey
- Department of Materials Science and Engineering, Faculty of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands
| | - Thijs J H Vlugt
- Engineering Thermodynamics, Process and Energy Department, Faculty of Mechanical Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, The Netherlands
| | - Othonas A Moultos
- Engineering Thermodynamics, Process and Energy Department, Faculty of Mechanical Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, The Netherlands
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2
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Sedano LF, Blazquez S, Vega C. Accuracy limit of non-polarizable four-point water models: TIP4P/2005 vs OPC. Should water models reproduce the experimental dielectric constant? J Chem Phys 2024; 161:044505. [PMID: 39046346 DOI: 10.1063/5.0211871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 06/30/2024] [Indexed: 07/25/2024] Open
Abstract
The last generation of four center non-polarizable models of water can be divided into two groups: those reproducing the dielectric constant of water, as OPC, and those significantly underestimating its value, as TIP4P/2005. To evaluate the global performance of OPC and TIP4P/2005, we shall follow the test proposed by Vega and Abascal in 2011 evaluating about 40 properties to fairly address this comparison. The liquid-vapor and liquid-solid equilibria are computed, as well as the heat capacities, isothermal compressibilities, surface tensions, densities of different ice polymorphs, the density maximum, equations of state at high pressures, and transport properties. General aspects of the phase diagram are considered by comparing the ratios of different temperatures (namely, the temperature of maximum density, the melting temperature of hexagonal ice, and the critical temperature). The final scores are 7.2 for TIP4P/2005 and 6.3 for OPC. The results of this work strongly suggest that we have reached the limit of what can be achieved with non-polarizable models of water and that the attempt to reproduce the experimental dielectric constant deteriorates the global performance of the water force field. The reason is that the dielectric constant depends on two surfaces (potential energy and dipole moment surfaces), whereas in the absence of an electric field, all properties can be determined simply from just one surface (the potential energy surface). The consequences of the choice of the water model in the modeling of electrolytes in water are also discussed.
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Affiliation(s)
- L F Sedano
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - S Blazquez
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - C Vega
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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3
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Habibi P, Polat HM, Blazquez S, Vega C, Dey P, Vlugt TJH, Moultos OA. Accurate Free Energies of Aqueous Electrolyte Solutions from Molecular Simulations with Non-polarizable Force Fields. J Phys Chem Lett 2024; 15:4477-4485. [PMID: 38634502 PMCID: PMC11057036 DOI: 10.1021/acs.jpclett.4c00428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 04/11/2024] [Accepted: 04/12/2024] [Indexed: 04/19/2024]
Abstract
Non-polarizable force fields fail to accurately predict free energies of aqueous electrolytes without compromising the predictive ability for densities and transport properties. A new approach is presented in which (1) TIP4P/2005 water and scaled charge force fields are used to describe the interactions in the liquid phase and (2) an additional Effective Charge Surface (ECS) is used to compute free energies at zero additional computational expense. The ECS is obtained using a single temperature-independent charge scaling parameter per species. Thereby, the chemical potential of water and the free energies of hydration of various aqueous salts (e.g., NaCl and LiCl) are accurately described (deviations less than 5% from experiments), in sharp contrast to calculations where the ECS is omitted (deviations larger than 20%). This approach enables accurate predictions of free energies of aqueous electrolyte solutions using non-polarizable force fields, without compromising liquid-phase properties.
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Affiliation(s)
- Parsa Habibi
- Engineering
Thermodynamics, Process & Energy Department, Faculty of Mechanical
Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, Netherlands
- Department
of Materials Science and Engineering, Faculty of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, Netherlands
| | - H. Mert Polat
- Engineering
Thermodynamics, Process & Energy Department, Faculty of Mechanical
Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, Netherlands
| | - Samuel Blazquez
- Departamento
de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Carlos Vega
- Departamento
de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Poulumi Dey
- Department
of Materials Science and Engineering, Faculty of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, Netherlands
| | - Thijs J. H. Vlugt
- Engineering
Thermodynamics, Process & Energy Department, Faculty of Mechanical
Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, Netherlands
| | - Othonas A. Moultos
- Engineering
Thermodynamics, Process & Energy Department, Faculty of Mechanical
Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, Netherlands
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4
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Cruces Chamorro V, Jungwirth P, Martinez-Seara H. Building Water Models Compatible with Charge Scaling Molecular Dynamics. J Phys Chem Lett 2024; 15:2922-2928. [PMID: 38451169 PMCID: PMC10945568 DOI: 10.1021/acs.jpclett.4c00344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 02/29/2024] [Accepted: 03/04/2024] [Indexed: 03/08/2024]
Abstract
Charge scaling has proven to be an efficient way to account in a mean-field manner for electronic polarization by aqueous ions in force field molecular dynamics simulations. However, commonly used water models with dielectric constants over 50 are not consistent with this approach leading to "overscaling", i.e., generally too weak ion-ion interactions. Here, we build water models fully compatible with charge scaling, i.e., having the correct low-frequency dielectric constant of about 45. To this end, we employ advanced optimization and machine learning schemes in order to explore the vast parameter space of four-site water models efficiently. As an a priori unwarranted positive result, we find a sizable range of force field parameters that satisfy the above dielectric constant constraint providing at the same time accuracy with respect to experimental data comparable with the best existing four-site water models such as TIP4P/2005, TIP4P-FB, or OPC. The present results thus open the way to the development of a consistent charge scaling force field for modeling ions in aqueous solutions.
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Affiliation(s)
- Victor Cruces Chamorro
- Institute of Organic Chemistry and
Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Pavel Jungwirth
- Institute of Organic Chemistry and
Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Hector Martinez-Seara
- Institute of Organic Chemistry and
Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
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5
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Blazquez S, Bourg IC, Vega C. Madrid-2019 force field: An extension to divalent cations Sr2+ and Ba2. J Chem Phys 2024; 160:046101. [PMID: 38270237 DOI: 10.1063/5.0186233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 12/27/2023] [Indexed: 01/26/2024] Open
Abstract
In this work, we present a parameterization of Sr2+ and Ba2+ cations, which expands the alkali earth set of cations of the Madrid-2019 force field. We have tested the model against the experimental densities of eight different salts, namely, SrCl2, SrBr2, SrI2, Sr(NO3)2, BaCl2, BaBr2, BaI2, and Ba(NO3)2. The force field is able to reproduce the experimental densities of all these salts up to their solubility limit. Furthermore, we have computed the viscosities for two selected salts, finding that the experimental values are overestimated, but the predictions are still reasonable. Finally, the structural properties for all the salts have been calculated with this model and align remarkably well with experimental observations.
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Affiliation(s)
- S Blazquez
- Dpto. Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Ian C Bourg
- Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey 08544, USA
- High Meadows Environmental Institute, Princeton University, Princeton, New Jersey 08544, USA
| | - C Vega
- Dpto. Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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6
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Perrone M, Capelli R, Empereur-mot C, Hassanali A, Pavan GM. Lessons Learned from Multiobjective Automatic Optimizations of Classical Three-Site Rigid Water Models Using Microscopic and Macroscopic Target Experimental Observables. JOURNAL OF CHEMICAL AND ENGINEERING DATA 2023; 68:3228-3241. [PMID: 38115916 PMCID: PMC10726314 DOI: 10.1021/acs.jced.3c00538] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 11/17/2023] [Accepted: 11/21/2023] [Indexed: 12/21/2023]
Abstract
The development of accurate water models is of primary importance for molecular simulations. Despite their intrinsic approximations, three-site rigid water models are still ubiquitously used to simulate a variety of molecular systems. Automatic optimization approaches have been recently used to iteratively refine three-site water models to fit macroscopic (average) thermodynamic properties, providing state-of-the-art three-site models that still present some deviations from the liquid water properties. Here, we show the results obtained by automatically optimizing three-site rigid water models to fit a combination of microscopic and macroscopic experimental observables. We use Swarm-CG, a multiobjective particle-swarm-optimization algorithm, for training the models to reproduce the experimental radial distribution functions of liquid water at various temperatures (rich in microscopic-level information on, e.g., the local orientation and interactions of the water molecules). We systematically analyze the agreement of these models with experimental observables and the effect of adding macroscopic information to the training set. Our results demonstrate how adding microscopic-rich information in the training of water models allows one to achieve state-of-the-art accuracy in an efficient way. Limitations in the approach and in the approximated description of water in these three-site models are also discussed, providing a demonstrative case useful for the optimization of approximated molecular models, in general.
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Affiliation(s)
- Mattia Perrone
- Department
of Applied Science and Technology, Politecnico
di Torino, Corso Duca degli Abruzzi 24, Torino I-10129, Italy
| | - Riccardo Capelli
- Department
of Biosciences, Università degli
Studi di Milano, Via Celoria 26, Milano I-20133, Italy
| | - Charly Empereur-mot
- Department
of Innovative Technologies, University of Applied Sciences and Arts
of Southern Switzerland, Polo Universitario
Lugano, Campus Est, Via
la Santa 1, Lugano-Viganello CH-6962, Switzerland
| | - Ali Hassanali
- The
Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, Trieste 34151, Italy
| | - Giovanni M. Pavan
- Department
of Applied Science and Technology, Politecnico
di Torino, Corso Duca degli Abruzzi 24, Torino I-10129, Italy
- Department
of Innovative Technologies, University of Applied Sciences and Arts
of Southern Switzerland, Polo Universitario
Lugano, Campus Est, Via
la Santa 1, Lugano-Viganello CH-6962, Switzerland
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7
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Blazquez S, Abascal JLF, Lagerweij J, Habibi P, Dey P, Vlugt TJH, Moultos OA, Vega C. Computation of Electrical Conductivities of Aqueous Electrolyte Solutions: Two Surfaces, One Property. J Chem Theory Comput 2023; 19:5380-5393. [PMID: 37506381 PMCID: PMC10448725 DOI: 10.1021/acs.jctc.3c00562] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Indexed: 07/30/2023]
Abstract
In this work, we computed electrical conductivities under ambient conditions of aqueous NaCl and KCl solutions by using the Einstein-Helfand equation. Common force fields (charge q = ±1 e) do not reproduce the experimental values of electrical conductivities, viscosities, and diffusion coefficients. Recently, we proposed the idea of using different charges to describe the potential energy surface (PES) and the dipole moment surface (DMS). In this work, we implement this concept. The equilibrium trajectories required to evaluate electrical conductivities (within linear response theory) were obtained by using scaled charges (with the value q = ±0.75 e) to describe the PES. The potential parameters were those of the Madrid-Transport force field, which accurately describe viscosities and diffusion coefficients of these ionic solutions. However, integer charges were used to compute the conductivities (thus describing the DMS). The basic idea is that although the scaled charge describes the ion-water interaction better, the integer charge reflects the value of the charge that is transported due to the electric field. The agreement obtained with experiments is excellent, as for the first time electrical conductivities (and the other transport properties) of NaCl and KCl electrolyte solutions are described with high accuracy for the whole concentration range up to their solubility limit. Finally, we propose an easy way to obtain a rough estimate of the actual electrical conductivity of the potential model under consideration using the approximate Nernst-Einstein equation, which neglects correlations between different ions.
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Affiliation(s)
- Samuel Blazquez
- Dpto.
Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Jose L. F. Abascal
- Dpto.
Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Jelle Lagerweij
- Engineering
Thermodynamics, Process and Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
| | - Parsa Habibi
- Engineering
Thermodynamics, Process and Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
- Department
of Materials Science and Engineering, Faculty of Mechanical, Maritime
and Materials Engineering, Delft University
of Technology, Mekelweg
2, 2628CD Delft, The Netherlands
| | - Poulumi Dey
- Department
of Materials Science and Engineering, Faculty of Mechanical, Maritime
and Materials Engineering, Delft University
of Technology, Mekelweg
2, 2628CD Delft, The Netherlands
| | - Thijs J. H. Vlugt
- Engineering
Thermodynamics, Process and Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
| | - Othonas A. Moultos
- Engineering
Thermodynamics, Process and Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
| | - Carlos Vega
- Dpto.
Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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8
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Han B, Isborn CM, Shi L. Incorporating Polarization and Charge Transfer into a Point-Charge Model for Water Using Machine Learning. J Phys Chem Lett 2023; 14:3869-3877. [PMID: 37067482 DOI: 10.1021/acs.jpclett.3c00036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Rigid nonpolarizable water models with fixed point charges have been widely employed in molecular dynamics simulations due to their efficiency and reasonable accuracy for the potential energy surface. However, the dipole moment surface of water is not necessarily well-described by the same fixed charges, leading to failure in reproducing dipole-related properties. Here, we developed a machine-learning model trained against electronic structure data to assign point charges for water, and the resulting dipole moment surface significantly improved the predictions of the dielectric constant and the low-frequency IR spectrum of liquid water. Our analysis reveals that within our atom-centered point-charge description of the dipole moment surface, the intermolecular charge transfer is the major source of the peak intensity at 200 cm-1, whereas the intramolecular polarization controls the enhancement of the dielectric constant. The effects of exact Hartree-Fock exchange in the hybrid density functional on these properties are also discussed.
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Affiliation(s)
- Bowen Han
- Chemistry and Biochemistry, University of California, Merced, California 95343, United States
| | - Christine M Isborn
- Chemistry and Biochemistry, University of California, Merced, California 95343, United States
| | - Liang Shi
- Chemistry and Biochemistry, University of California, Merced, California 95343, United States
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9
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Jorge M, Barrera MC, Milne AW, Ringrose C, Cole DJ. What is the Optimal Dipole Moment for Nonpolarizable Models of Liquids? J Chem Theory Comput 2023; 19:1790-1804. [PMID: 36827585 DOI: 10.1021/acs.jctc.2c01123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
In classical nonpolarizable models, electrostatic interactions are usually described by assigning fixed partial charges to interaction sites. Despite the multitude of methods and theories proposed over the years for partial charge assignment, a fundamental question remains─what is the correct degree of polarization that a fixed-charge model should possess to provide the best balance of interactions (including induction effects) and yield the best description of the potential energy surface of a liquid phase? We address this question by approaching it from two separate and independent viewpoints: the QUantum mechanical BEspoke (QUBE) approach, which assigns bespoke force field parameters for individual molecules from ab initio calculations with minimal empirical fitting, and the Polarization-Consistent Approach (PolCA) force field, based on empirical fitting of force field parameters with an emphasis on transferability by rigorously accounting for polarization effects in the parameterization process. We show that the two approaches yield consistent answers to the above question, namely, that the dipole moment of the model should be approximately halfway between those of the gas and the liquid phase. Crucially, however, the reference liquid-phase dipole needs to be estimated using methods that explicitly consider both mean-field and local contributions to polarization. In particular, continuum dielectric models are inadequate for this purpose because they cannot account for local effects and therefore significantly underestimate the degree of polarization of the molecule. These observations have profound consequences for the development, validation, and testing of nonpolarizable models.
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Affiliation(s)
- Miguel Jorge
- Department of Chemical and Process Engineering, University of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom
| | - Maria Cecilia Barrera
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral St, Glasgow G4 0RE, United Kingdom
| | - Andrew W Milne
- Department of Chemical and Process Engineering, University of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom
| | - Chris Ringrose
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Daniel J Cole
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
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10
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Blazquez S, Conde MM, Vega C. Scaled charges for ions: An improvement but not the final word for modeling electrolytes in water. J Chem Phys 2023; 158:054505. [PMID: 36754806 DOI: 10.1063/5.0136498] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
In this work, we discuss the use of scaled charges when developing force fields for NaCl in water. We shall develop force fields for Na+ and Cl- using the following values for the scaled charge (in electron units): ±0.75, ±0.80, ±0.85, and ±0.92 along with the TIP4P/2005 model of water (for which previous force fields were proposed for q = ±0.85 and q = ±1). The properties considered in this work are densities, structural properties, transport properties, surface tension, freezing point depression, and maximum in density. All the developed models were able to describe quite well the experimental values of the densities. Structural properties were well described by models with charges equal to or larger than ±0.85, surface tension by the charge ±0.92, maximum in density by the charge ±0.85, and transport properties by the charge ±0.75. The use of a scaled charge of ±0.75 is able to reproduce with high accuracy the viscosities and diffusion coefficients of NaCl solutions for the first time. We have also considered the case of KCl in water, and the results obtained were fully consistent with those of NaCl. There is no value of the scaled charge able to reproduce all the properties considered in this work. Although certainly scaled charges are not the final word in the development of force fields for electrolytes in water, its use may have some practical advantages. Certain values of the scaled charge could be the best option when the interest is to describe certain experimental properties.
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Affiliation(s)
- S Blazquez
- Dpto. Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - M M Conde
- Departamento de Ingeniería Química Industrial y Medio Ambiente, Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain
| | - C Vega
- Dpto. Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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11
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Building a Hofmeister-like series for the maximum in density temperature of aqueous electrolyte solutions. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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12
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Abstract
Simulating water accurately has been a major challenge in atomistic simulations for decades. Inclusion of electronic polarizability effects holds considerable promise, yet existing approaches suffer from significant computational overheads compared to the widely used nonpolarizable water models. We have developed a globally optimal polarizable water model, OPC3-pol, that explicitly accounts for electronic polarizability with minimal impact on the computational efficiency. OPC3-pol reproduces five key bulk water properties at room temperature with an average relative error of 0.6%. In atomistic simulations, OPC3-pol's computational efficiency is in between that of 3- and 4-point nonpolarizable models; the model supports increased (4 fs) integration time step. OPC3-pol is tested in simulations of globular protein ubiquitin and a B-DNA dodecamer with several AMBER force fields, ff99SB, ff14SB, ff19SB, and OL15, demonstrating structure stability close to reference on multi-microsecond time scale. Simulation of an intrinsically disordered amyloid β-peptide yields an ensemble with the radius of gyration of a random coil. The proposed water model can be trivially adopted by any package that supports standard nonpolarizable force fields and water models; its intended use is in long classical atomistic simulations where water polarization effects are expected to be important.
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Affiliation(s)
- Yeyue Xiong
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg24061, United States
| | - Saeed Izadi
- Pharmaceutical Development Department, Genentech, South San Francisco94080, United States
| | - Alexey V Onufriev
- Department of Computer Science, Virginia Tech, Blacksburg24061, United States
- Department of Physics, Virginia Tech, Blacksburg24061, United States
- Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg24061, United States
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13
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Polarizable force fields for accurate molecular simulations of aqueous solutions of electrolytes, crystalline salts, and solubility: Li+, Na+, K+, Rb+, F−, Cl−, Br−, I−. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119659] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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14
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Abstract
By using the direct coexistence method, we have calculated the melting points of ice I h at normal pressure for three recently proposed water models, namely, TIP3P-FB, TIP4P-FB, and TIP4P-D. We obtained T m = 216 K for TIP3P-FB, T m = 242 K for TIP4P-FB, and T m = 247 K for TIP4P-D. We revisited the melting point of TIP4P/2005 and TIP5P obtaining T m = 250 and 274 K, respectively. We summarize the current situation of the melting point of ice I h for a number of water models and conclude that no model is yet able to simultaneously reproduce the melting temperature of ice I h and the temperature of the maximum in density at room pressure. This probably points toward our both still incomplete knowledge of the potential energy surface of water and the necessity of incorporating nuclear quantum effects to describe both properties simultaneously.
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Affiliation(s)
- S. Blazquez
- Dpto. Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - C. Vega
- Dpto. Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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15
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16
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Sedano LF, Blazquez S, Noya EG, Vega C, Troncoso J. Maximum in density of electrolyte solutions: Learning about ion-water interactions and testing the Madrid-2019 force field. J Chem Phys 2022; 156:154502. [PMID: 35459318 DOI: 10.1063/5.0087679] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work, we studied the effect of Li+, Na+, K+, Mg2+, and Ca2+ chlorides and sulfates on the temperature of maximum density (TMD) of aqueous solutions at room pressure. Experiments at 1 molal salt concentration were carried out to determine the TMD of these solutions. We also performed molecular dynamics simulations to estimate the TMD at 1 and 2 m with the Madrid-2019 force field, which uses the TIP4P/2005 water model and scaled charges for the ions, finding an excellent agreement between experiment and simulation. All the salts studied in this work shift the TMD of the solution to lower temperatures and flatten the density vs temperature curves (when compared to pure water) with increasing salt concentration. The shift in the TMD depends strongly on the nature of the electrolyte. In order to explore this dependence, we have evaluated the contribution of each ion to the shift in the TMD concluding that Na+, Ca2+, and SO4 2- seem to induce the largest changes among the studied ions. The volume of the system has been analyzed for salts with the same anion and different cations. These curves provide insight into the effect of different ions upon the structure of water. We claim that the TMD of electrolyte solutions entails interesting physics regarding ion-water and water-water interactions and should, therefore, be considered as a test property when developing force fields for electrolytes. This matter has been rather unnoticed for almost a century now and we believe it is time to revisit it.
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Affiliation(s)
- L F Sedano
- Depto. Química Física I (Unidad Asociada de I+D+i al CSIC), Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - S Blazquez
- Depto. Química Física I (Unidad Asociada de I+D+i al CSIC), Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - E G Noya
- Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, CSIC, Calle Serrano 119, 28006 Madrid, Spain
| | - C Vega
- Depto. Química Física I (Unidad Asociada de I+D+i al CSIC), Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - J Troncoso
- Departamento de Física Aplicada, Universidad de Vigo, Facultad de Ciencias del Campus de Ourense, E 32004 Ourense, Spain
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17
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Tran L, Škvára J, Smith WR. Atomistic simulation framework for molten salt vapor–liquid equilibrium prediction and its application to NaCl. J Chem Phys 2022; 156:144501. [DOI: 10.1063/5.0089455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Knowledge of the vapor–liquid equilibrium (VLE) properties of molten salts is important in the design of thermal energy storage systems for solar power and nuclear energy production applications. The high temperatures involved make their experimental determination problematic, and the development of both macroscopic thermodynamic correlations and predictive molecular-based methodologies are complicated by the requirement to appropriately incorporate the chemically reacting vapor-phase species. We derive a general thermodynamic-based atomistic simulation framework for molten salt VLE prediction and show its application to NaCl. Its input quantities are temperature-dependent ideal-gas free energy data for the vapor phase reactions and density and residual chemical potential data for the liquid. If these are not available experimentally, the former may be predicted using standard electronic structure software, and the latter may be predicted by means of classical atomistic simulation methodology. The framework predicts the temperature dependence of vapor pressure, coexisting phase densities, vapor phase composition, and vaporization enthalpy. It also predicts the concentrations of vapor phase species present in minor amounts (such as the free ions), quantities that are extremely difficult to measure experimentally. We furthermore use the results to obtain an approximation to the complete VLE binodal dome and the critical properties. We verify the framework for molten NaCl, for which experimentally based density and chemical potential data are available in the literature. We then apply it to the analysis of NaCl simulation data for two commonly used atomistic force fields. The framework can be readily extended to molten salt mixtures and to ionic liquids.
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Affiliation(s)
- Leann Tran
- Department of Mathematics and Statistics, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Jiří Škvára
- Institute of Chemical Process Fundamentals, Czech Academy of Sciences, Prague 6, Suchdol, Czech Republic
| | - William R. Smith
- Department of Mathematics and Statistics, University of Guelph, Guelph, Ontario N1G 2W1, Canada
- Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Faculty of Science, Ontario Tech University, Oshawa, Ontario L1H 7K4, Canada
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18
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Lamas CP, Vega C, Noya EG. Freezing point depression of salt aqueous solutions using the Madrid-2019 model. J Chem Phys 2022; 156:134503. [PMID: 35395902 DOI: 10.1063/5.0085051] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Salt aqueous solutions are relevant in many fields, ranging from biological systems to seawater. Thus, the availability of a force-field that is able to reproduce the thermodynamic and dynamic behavior of salt aqueous solutions would be of great interest. Unfortunately, this has been proven challenging, and most of the existing force-fields fail to reproduce much of their behavior. In particular, the diffusion of water or the salt solubility are often not well reproduced by most of the existing force-fields. Recently, the Madrid-2019 model was proposed, and it was shown that this force-field, which uses the TIP4P/2005 model for water and non-integer charges for the ions, provides a good description of a large number of properties, including the solution densities, viscosities, and the diffusion of water. In this work, we assess the performance of this force-field on the evaluation of the freezing point depression. Although the freezing point depression is a colligative property that at low salt concentrations depends solely on properties of pure water, a good model for the electrolytes is needed to accurately predict the freezing point depression at moderate and high salt concentrations. The coexistence line between ice and several salt aqueous solutions (NaCl, KCl, LiCl, MgCl2, and Li2SO4) up to the eutectic point is estimated from direct coexistence molecular dynamics simulations. Our results show that this force-field reproduces fairly well the experimentally measured freezing point depression with respect to pure water freezing for all the salts and at all the compositions considered.
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Affiliation(s)
- Cintia P Lamas
- Departamento de Química-Física I (Unidad de I+D+i Asociada al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Carlos Vega
- Departamento de Química-Física I (Unidad de I+D+i Asociada al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Eva G Noya
- Instituto de Química Física Rocasolano, CSIC, C/ Serrano 119, 28006 Madrid, Spain
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19
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Blazquez S, Conde MM, Abascal JLF, Vega C. The Madrid-2019 force field for electrolytes in water using TIP4P/2005 and scaled charges: Extension to the ions F−, Br−, I−, Rb+, and Cs+. J Chem Phys 2022; 156:044505. [DOI: 10.1063/5.0077716] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- S. Blazquez
- Departamento Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - M. M. Conde
- Departamento de Ingeniería Química Industrial y Medio Ambiente, Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, 28006 Madrid, Spain
| | - J. L. F. Abascal
- Departamento Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - C. Vega
- Departamento Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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20
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Zhang X, Wang Y, Yao J, Li H, Mochizuki K. A tiny charge-scaling in the OPLS-AA + L-OPLS force field delivers the realistic dynamics and structure of liquid primary alcohols. J Comput Chem 2021; 43:421-430. [PMID: 34962297 DOI: 10.1002/jcc.26802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/07/2021] [Accepted: 12/10/2021] [Indexed: 11/06/2022]
Abstract
We carry out molecular dynamics simulations for pure liquid primary alcohols ranging from methanol to 1-decanol under ambient conditions. Based on the OPLS-AA force field with the L-OPLS correction, we demonstrate that a few % increases in the partial charges deliver the realistic dynamics (self-diffusion coefficient and shear viscosity) and structure (density and X-ray scattering intensity) as well as enthalpy of vaporization and isothermal compressibility. The validity against thermal expansion coefficient, isobaric heat capacity, and static dielectric constant are also discussed.
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Affiliation(s)
- Xuan Zhang
- Department of Chemistry, Zhejiang University, Hangzhou, People's Republic of China
| | - Yongtao Wang
- Department of Chemistry, Zhejiang University, Hangzhou, People's Republic of China
| | - Jia Yao
- Department of Chemistry, Zhejiang University, Hangzhou, People's Republic of China
| | - Haoran Li
- Department of Chemistry, Zhejiang University, Hangzhou, People's Republic of China
| | - Kenji Mochizuki
- Department of Chemistry, Zhejiang University, Hangzhou, People's Republic of China
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21
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Garaizar A, Espinosa JR. Salt dependent phase behavior of intrinsically disordered proteins from a coarse-grained model with explicit water and ions. J Chem Phys 2021; 155:125103. [PMID: 34598583 DOI: 10.1063/5.0062687] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Multivalent proteins and nucleic acids can self-assemble into biomolecular condensates that contribute to compartmentalize the cell interior. Computer simulations offer a unique view to elucidate the mechanisms and key intermolecular interactions behind the dynamic formation and dissolution of these condensates. In this work, we present a novel approach to include explicit water and salt in sequence-dependent coarse-grained (CG) models for proteins and RNA, enabling the study of biomolecular condensate formation in a salt-dependent manner. Our framework combines a reparameterized version of the HPS protein force field with the monoatomic mW water model and the mW-ion potential for NaCl. We show how our CG model qualitatively captures the experimental radius of the gyration trend of a subset of intrinsically disordered proteins and reproduces the experimental protein concentration and water percentage of the human fused in sarcoma (FUS) low-complexity-domain droplets at physiological salt concentration. Moreover, we perform seeding simulations as a function of salt concentration for two antagonist systems: the engineered peptide PR25 and poly-uridine/poly-arginine mixtures, finding good agreement with their reported in vitro phase behavior with salt concentration in both cases. Taken together, our work represents a step forward towards extending sequence-dependent CG models to include water and salt, and to consider their key role in biomolecular condensate self-assembly.
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Affiliation(s)
- Adiran Garaizar
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Jorge R Espinosa
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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22
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Jorge M, Milne AW, Barrera MC, Gomes JR. New Force-Field for Organosilicon Molecules in the Liquid Phase. ACS PHYSICAL CHEMISTRY AU 2021; 1:54-69. [PMID: 34939073 PMCID: PMC8679648 DOI: 10.1021/acsphyschemau.1c00014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Indexed: 11/29/2022]
Abstract
In this paper, we present a new molecular model that can accurately predict thermodynamic liquid state and phase-change properties for organosilicon molecules including several functional groups (alkylsilane, alkoxysilane, siloxane, and silanol). These molecules are of great importance in geological processes, biological systems, and material science, yet no force field currently exists that is widely applicable to organosilicates. The model is parametrized according to the recent Polarization-Consistent Approach (PolCA), which allows for polarization effects to be incorporated into a nonpolarizable model through post facto correction terms and is therefore consistent with previous parametrizations of the PolCA force field. Alkyl groups are described by the United-Atom approach, bond and angle parameters were taken from previous literature studies, dihedral parameters were fitted to new quantum chemical energy profiles, point charges were calculated from quantum chemical optimizations in a continuum solvent, and Lennard-Jones dispersion/repulsion parameters were fitted to match the density and enthalpy of vaporization of a small number of selected compounds. Extensive validation efforts were carried out, after careful collection and curation of experimental data for organosilicates. Overall, the model performed quite well for the density, enthalpy of vaporization, dielectric constant, and self-diffusion coefficient, but it slightly overestimated the magnitude of self-solvation free energies. The modular and transferable nature of the PolCA force field allows for further extensions to other types of silicon-containing compounds.
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Affiliation(s)
- Miguel Jorge
- Department
of Chemical and Process Engineering, University
of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom,
| | - Andrew W. Milne
- Department
of Chemical and Process Engineering, University
of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom
| | - Maria Cecilia Barrera
- Department
of Chemical and Process Engineering, University
of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom
| | - José R.
B. Gomes
- CICECO
− Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
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23
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24
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Balancing the structural, vibrational and dielectric properties of an advanced flexible water model. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2020.138172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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25
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Amezcua M, El Khoury L, Mobley DL. SAMPL7 Host-Guest Challenge Overview: assessing the reliability of polarizable and non-polarizable methods for binding free energy calculations. J Comput Aided Mol Des 2021; 35:1-35. [PMID: 33392951 PMCID: PMC8121194 DOI: 10.1007/s10822-020-00363-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 11/24/2020] [Indexed: 12/15/2022]
Abstract
The SAMPL challenges focus on testing and driving progress of computational methods to help guide pharmaceutical drug discovery. However, assessment of methods for predicting binding affinities is often hampered by computational challenges such as conformational sampling, protonation state uncertainties, variation in test sets selected, and even lack of high quality experimental data. SAMPL blind challenges have thus frequently included a component focusing on host-guest binding, which removes some of these challenges while still focusing on molecular recognition. Here, we report on the results of the SAMPL7 blind prediction challenge for host-guest affinity prediction. In this study, we focused on three different host-guest categories-a familiar deep cavity cavitand series which has been featured in several prior challenges (where we examine binding of a series of guests to two hosts), a new series of cyclodextrin derivatives which are monofunctionalized around the rim to add amino acid-like functionality (where we examine binding of two guests to a series of hosts), and binding of a series of guests to a new acyclic TrimerTrip host which is related to previous cucurbituril hosts. Many predictions used methods based on molecular simulations, and overall success was mixed, though several methods stood out. As in SAMPL6, we find that one strategy for achieving reasonable accuracy here was to make empirical corrections to binding predictions based on previous data for host categories which have been studied well before, though this can be of limited value when new systems are included. Additionally, we found that alchemical free energy methods using the AMOEBA polarizable force field had considerable success for the two host categories in which they participated. The new TrimerTrip system was also found to introduce some sampling problems, because multiple conformations may be relevant to binding and interconvert only slowly. Overall, results in this challenge tentatively suggest that further investigation of polarizable force fields for these challenges may be warranted.
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Affiliation(s)
- Martin Amezcua
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, 92697, USA
| | - Léa El Khoury
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, 92697, USA
| | - David L Mobley
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, 92697, USA.
- Department of Chemistry, University of California, Irvine, CA, 92697, USA.
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26
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Cardona J, Jorge M, Lue L. Simple corrections for the static dielectric constant of liquid mixtures from model force fields. Phys Chem Chem Phys 2020; 22:21741-21749. [PMID: 32959821 DOI: 10.1039/d0cp04034g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pair-wise additive force fields provide fairly accurate predictions, through classical molecular simulations, for a wide range of structural, thermodynamic, and dynamical properties of many materials. However, one key property that has not been well captured is the static dielectric constant, which characterizes the response of a system to an applied electric field and is important in determining the screening of electrostatic interactions through a system. A simple correction has been found to provide a relatively robust method to improve the estimate of the static dielectric constant from molecular simulations for a broad range of compounds. This approach accounts for the electronic contribution to molecular polarizability and assumes that the charges that couple a molecule to an applied electric field are proportional to the effective force field charges. In this work, we examine how this correction performs for systems at different temperatures and for binary mixtures. Using a value for the electronic polarizability, based on the experimental index of refraction, and a charge scaling factor, determined at a single temperature, we find that the static dielectric constant can be predicted remarkably well, in comparison to the experimentally measured values. This provides good evidence that the effective charges that appear in pair-wise additive force fields developed to reproduce the potential energy surface of a system are not the same as those that determine the static dielectric constant; however, they can be captured in a relatively simple manner, which is dependent on the particular force field.
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Affiliation(s)
- Javier Cardona
- Department of Chemical and Process Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ, UK. and Department of Electronic and Electrical Engineering, University of Strathclyde, Royal College Building, 204 George Street, Glasgow G1 1XW, UK
| | - Miguel Jorge
- Department of Chemical and Process Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ, UK.
| | - Leo Lue
- Department of Chemical and Process Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ, UK.
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27
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28
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Kolafa J. Pressure in Molecular Simulations with Scaled Charges. 1. Ionic Systems. J Phys Chem B 2020; 124:7379-7390. [PMID: 32790401 DOI: 10.1021/acs.jpcb.0c02641] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Charge scaling, rationalized as MDEC (molecular dynamics in electronic continuum) or ECC (electronic continuum correction), has become a widely used simple approach to how to avoid self-consistent induced dipoles yet approximately take into account the effects of electronic polarizability. It has been assumed that the continuum permittivity does not depend on density; in turn, pressure is calculated by standard formulas. In this work, we elaborate a complementary approximation of density-independent molecular polarizability and derive formulas for pressure corrections within the MDEC framework; real behavior lies between these two extremes. The pressure corrections for test ionic systems are huge and negative, leading to sizable densities in constant-pressure MDEC simulations. A comparison of MDEC results with equivalent polarizable systems gives a good pressure match for a crystal but very low MDEC pressures for ionic liquids. These results witness about the importance of a correct density dependence not only of continuum permittivity in MDEC simulations but also of polarizability in polarizable simulations.
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Affiliation(s)
- Jiří Kolafa
- Department of Physical Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Praha 6, Czech Republic
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29
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Kussainova D, Mondal A, Young JM, Yue S, Panagiotopoulos AZ. Molecular simulation of liquid-vapor coexistence for NaCl: Full-charge vs scaled-charge interaction models. J Chem Phys 2020; 153:024501. [PMID: 32668951 DOI: 10.1063/5.0012065] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Scaled-charge models have been recently introduced for molecular simulations of electrolyte solutions and molten salts to attempt to implicitly represent polarizability. Although these models have been found to accurately predict electrolyte solution dynamic properties, they have not been tested for coexistence properties, such as the vapor pressure of the melt. In this work, we evaluate the vapor pressure of a scaled-charge sodium chloride (NaCl) force field and compare the results against experiments and a non-polarizable full-charge force field. The scaled-charge force field predicts a higher vapor pressure than found in experiments, due to its overprediction of the liquid-phase chemical potential. Reanalyzing the trajectories generated from the scaled-charge model with full charges improves the estimation of the liquid-phase chemical potential but not the vapor pressure.
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Affiliation(s)
- Dina Kussainova
- Department of Chemical and Materials Engineering, School of Engineering and Digital Sciences, Nazarbayev University, Nur-Sultan, Kazakhstan
| | - Anirban Mondal
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Jeffrey M Young
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Shuwen Yue
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, USA
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30
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Le Breton G, Joly L. Molecular modeling of aqueous electrolytes at interfaces: Effects of long-range dispersion forces and of ionic charge rescaling. J Chem Phys 2020; 152:241102. [PMID: 32610967 DOI: 10.1063/5.0011058] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Molecular dynamics simulations of aqueous electrolytes generally rely on empirical force fields, combining dispersion interactions-described by a truncated Lennard-Jones (LJ) potential-and electrostatic interactions-described by a Coulomb potential computed with a long-range solver. Recently, force fields using rescaled ionic charges [electronic continuum correction (ECC)], possibly complemented with rescaling of LJ parameters [ECC rescaled (ECCR)], have shown promising results in bulk, but their performance at interfaces has been less explored. Here, we started by exploring the impact of the LJ potential truncation on the surface tension of a sodium chloride aqueous solution. We show a discrepancy between the numerical predictions for truncated LJ interactions with a large cutoff and for untruncated LJ interactions computed with a long-range solver, which can bias comparison of force field predictions with experiments. Using a long-range solver for LJ interactions, we then show that an ionic charge rescaling factor chosen to correct long-range electrostatic interactions in bulk accurately describes image charge repulsion at the liquid-vapor interface, and the rescaling of LJ parameters in ECCR models-aimed at capturing local ion-ion and ion-water interactions in bulk- describes well the formation of an ionic double layer at the liquid-vapor interface. Overall, these results suggest that the molecular modeling of aqueous electrolytes at interfaces would benefit from using long-range solvers for dispersion forces and from using ECCR models, where the charge rescaling factor should be chosen to correct long-range electrostatic interactions.
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Affiliation(s)
- Guillaume Le Breton
- Département de Physique, École Normale Supérieure de Lyon, 46 Allée d'Italie, Lyon Cedex 07, France
| | - Laurent Joly
- Univ. Lyon, Univ. Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
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31
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Saric D, Kohns M, Vrabec J. Dielectric constant and density of aqueous alkali halide solutions by molecular dynamics: A force field assessment. J Chem Phys 2020; 152:164502. [PMID: 32357782 DOI: 10.1063/1.5144991] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The concentration dependence of the dielectric constant and the density of 11 aqueous alkali halide solutions (LiCl, NaCl, KCl, RbCl, CsCl, LiI, NaI, KI, CsI, KF, and CsF) is investigated by molecular simulation. Predictions using eight non-polarizable ion force fields combined with the TIP4P/ε water model are compared to experimental data. The influence of the water model and the temperature on the results for the NaCl brine are also addressed. The TIP4P/ε water model improves the accuracy of dielectric constant predictions compared to the SPC/E water model. The solution density is predicted well by most ion models. Almost all ion force fields qualitatively capture the decline of the dielectric constant with the increase of concentration for all solutions and with the increase of temperature for NaCl brine. However, the sampled dielectric constant is mostly in poor quantitative agreement with experimental data. These results are related to the microscopic solution structure, ion pairing, and ultimately the force field parameters. Ion force fields with excessive contact ion pairing and precipitation below the experimental solubility limit generally yield higher dielectric constant values. An adequate reproduction of the experimental solubility limit should therefore be a prerequisite for further investigations of the dielectric constant of aqueous electrolyte solutions by molecular simulation.
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Affiliation(s)
- Denis Saric
- Thermodynamics and Energy Technology, University of Paderborn, 33098 Paderborn, Germany
| | - Maximilian Kohns
- Laboratory of Engineering Thermodynamics, Technische Universität Kaiserslautern, 67633 Kaiserslautern, Germany
| | - Jadran Vrabec
- Thermodynamics and Process Engineering, Technical University Berlin, 10587 Berlin, Germany
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32
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Barrera M, Jorge M. A Polarization-Consistent Model for Alcohols to Predict Solvation Free Energies. J Chem Inf Model 2020; 60:1352-1367. [PMID: 31977210 PMCID: PMC7145284 DOI: 10.1021/acs.jcim.9b01005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Indexed: 11/28/2022]
Abstract
Classical nonpolarizable models, normally based on a combination of Lennard-Jones sites and point charges, are extensively used to model thermodynamic properties of fluids, including solvation. An important shortcoming of these models is that they do not explicitly account for polarization effects, i.e., a description of how the electron density responds to changes in the molecular environment. Instead, polarization is implicitly included, in a mean-field sense, into the parameters of the model, usually by fitting to pure liquid properties (e.g., density). This causes problems when trying to describe thermodynamic properties that involve a change of phase (e.g., enthalpy of vaporization), that directly depend on the electronic response of the medium (e.g., dielectric constant), and that require mixing or solvation in different media (e.g., solvation free energies). Fully polarizable models present a natural route for addressing these limitations but at the price of a much higher computational cost. In this work, we combine the best of those two approaches by running fast simulations using nonpolarizable models and applying post facto corrections to the computed properties in order to account for the effects of polarization. By applying this new paradigm, a new united-atom force field for alcohols is developed that is able to predict both pure liquid properties, including dielectric constant, and solvation free energies in different solvents with a high degree of accuracy. This paves the way for the development of a generic classical nonpolarizable force field that can predict solvation of drug-like molecules in a variety of solvents.
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Affiliation(s)
- Maria
Cecilia Barrera
- Department of Chemical and
Process Engineering, University of Strathclyde, Glasgow G1 1XJ, United Kingdom
| | - Miguel Jorge
- Department of Chemical and
Process Engineering, University of Strathclyde, Glasgow G1 1XJ, United Kingdom
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33
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Sommers GM, Calegari Andrade MF, Zhang L, Wang H, Car R. Raman spectrum and polarizability of liquid water from deep neural networks. Phys Chem Chem Phys 2020; 22:10592-10602. [DOI: 10.1039/d0cp01893g] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Using deep neural networks to model the polarizability and potential energy surfaces, we compute the Raman spectrum of liquid water at several temperatures with ab initio molecular dynamics accuracy.
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Affiliation(s)
| | | | - Linfeng Zhang
- Program in Applied and Computational Mathematics
- Princeton University
- Princeton
- USA
| | - Han Wang
- Laboratory of Computational Physics
- Institute of Applied Physics and Computational Mathematics
- Beijing 100088
- P. R. China
| | - Roberto Car
- Department of Physics
- Princeton University
- Princeton
- USA
- Department of Chemistry
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34
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Kopanichuk IV, Novikov VA, Vanin AA, Brodskaya EN. The electric properties of AOT reverse micelles by molecular dynamics simulations. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.111960] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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35
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Exploring optimization strategies for improving explicit water models: Rigid n-point model and polarizable model based on Drude oscillator. PLoS One 2019; 14:e0224991. [PMID: 31725740 PMCID: PMC6855648 DOI: 10.1371/journal.pone.0224991] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 10/25/2019] [Indexed: 11/20/2022] Open
Abstract
Rigid n-point water models are widely used in atomistic simulations, but have known accuracy drawbacks. Increasing the number of point charges, as well as adding electronic polarizability, are two common strategies for accuracy improvements. Both strategies come at considerable computational cost, which weighs heavily against modest possible accuracy improvements in practical simulations. In an effort to provide guidance for model development, here we have explored the limiting accuracy of "electrostatically globally optimal" n-point water models in terms of their ability to reproduce properties of water dimer-a mimic of the condensed state of water. For a given n, each model is built upon a set of reference multipole moments (e.g. ab initio) and then optimized to reproduce water dimer total dipole moment. The models are then evaluated with respect to the accuracy of reproducing the geometry of the water dimer. We find that global optimization of the charge distribution alone can deliver high accuracy of the water model: for n = 4 or n = 5, the geometry of the resulting water dimer can be almost within 50 of the ab initio reference, which is half that of the experimental error margin. Thus, global optimization of the charge distribution of classical n-point water models can lead to high accuracy models. We also find that while the accuracy improvement in going from n = 3 to n = 4 is substantial, the additional accuracy increase in going from n = 4 to n = 5 is marginal. Next, we have explored accuracy limitations of the standard practice of adding electronic polarizability (via a Drude particle) to a "rigid base"-pre-optimization rigid n-point water model. The resulting model (n = 3) shows a relatively small improvement in accuracy, suggesting that the strategy of merely adding the polarizability to an inferior accuracy water model used as the base cannot fix the defects of the latter. An alternative strategy in which the parameters of the rigid base model are globally optimized along with the polarizability parameter is much more promising: the resulting 3-point polarizable model out-performs even the 5-point optimal rigid model by a large margin. We suggest that future development efforts consider 3- and 4-point polarizable models where global optimization of the "rigid base" is coupled to optimization of the polarizability to deliver globally optimal solutions.
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36
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Zeron IM, Abascal JLF, Vega C. A force field of Li +, Na +, K +, Mg 2+, Ca 2+, Cl -, and SO 4 2- in aqueous solution based on the TIP4P/2005 water model and scaled charges for the ions. J Chem Phys 2019; 151:134504. [PMID: 31594349 DOI: 10.1063/1.5121392] [Citation(s) in RCA: 131] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
In this work, a force field for several ions in water is proposed. In particular, we consider the cations Li+, Na+, K+, Mg2+, and Ca2+ and the anions Cl- and SO4 2-. These ions were selected as they appear in the composition of seawater, and they are also found in biological systems. The force field proposed (denoted as Madrid-2019) is nonpolarizable, and both water molecules and sulfate anions are rigid. For water, we use the TIP4P/2005 model. The main idea behind this work is to further explore the possibility of using scaled charges for describing ionic solutions. Monovalent and divalent ions are modeled using charges of 0.85 and 1.7, respectively (in electron units). The model allows a very accurate description of the densities of the solutions up to high concentrations. It also gives good predictions of viscosities up to 3 m concentrations. Calculated structural properties are also in reasonable agreement with the experiment. We have checked that no crystallization occurred in the simulations at concentrations similar to the solubility limit. A test for ternary mixtures shows that the force field provides excellent performance at an affordable computer cost. In summary, the use of scaled charges, which could be regarded as an effective and simple way of accounting for polarization (at least to a certain extend), improves the overall description of ionic systems in water. However, for purely ionic systems, scaled charges will not adequately describe neither the solid nor the melt.
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Affiliation(s)
- I M Zeron
- Depto. Química Física, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - J L F Abascal
- Depto. Química Física, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - C Vega
- Depto. Química Física, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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37
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Jorge M, Lue L. The dielectric constant: Reconciling simulation and experiment. J Chem Phys 2019; 150:084108. [DOI: 10.1063/1.5080927] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Miguel Jorge
- Department of Chemical and Process Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom
| | - Leo Lue
- Department of Chemical and Process Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom
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38
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Elton DC, Fritz M, Fernández-Serra M. Using a monomer potential energy surface to perform approximate path integral molecular dynamics simulation of ab initio water at near-zero added cost. Phys Chem Chem Phys 2018; 21:409-417. [PMID: 30534683 DOI: 10.1039/c8cp06077k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
It is now established that nuclear quantum motion plays an important role in determining water's hydrogen bonding, structure, and dynamics. Such effects are important to include in density functional theory (DFT) based molecular dynamics simulation of water. The standard way of treating nuclear quantum effects, path integral molecular dynamics (PIMD), multiplies the number of energy/force calculations by the number of beads required. In this work we introduce a method whereby PIMD can be incorporated into a DFT simulation with little extra cost and little loss in accuracy. The method is based on the many body expansion of the energy and has the benefit of including a monomer level correction to the DFT energy. Our method calculates intramolecular forces using the highly accurate monomer potential energy surface developed by Partridge-Schwenke, which is cheap to evaluate. Intermolecular forces and energies are calculated with DFT only once per timestep using the centroid positions. We show how our method may be used in conjunction with a multiple time step algorithm for an additional speedup and how it relates to ring polymer contraction and other schemes that have been introduced recently to speed up PIMD simulations. We show that our method, which we call "monomer PIMD", correctly captures changes in the structure of water found in a full PIMD simulation but at much lower computational cost.
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Affiliation(s)
- Daniel C Elton
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA.
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39
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Tsimpanogiannis IN, Moultos OA, Franco LFM, Spera MBDM, Erdős M, Economou IG. Self-diffusion coefficient of bulk and confined water: a critical review of classical molecular simulation studies. MOLECULAR SIMULATION 2018. [DOI: 10.1080/08927022.2018.1511903] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Ioannis N. Tsimpanogiannis
- Environmental Research Laboratory, National Center for Scientific Research “Demokritos”, Aghia Paraskevi Attikis, Greece
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, Aghia Paraskevi Attikis, Greece
| | - Othonas A. Moultos
- Engineering Thermodynamics, Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands
| | - Luís F. M. Franco
- School of Chemical Engineering, University of Campinas, Campinas, Brazil
| | | | - Máté Erdős
- Engineering Thermodynamics, Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Delft, The Netherlands
| | - Ioannis G. Economou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, Aghia Paraskevi Attikis, Greece
- Chemical Engineering Program, Texas A&M University at Qatar, Doha, Qatar
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40
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Affiliation(s)
- Xinzijian Liu
- Beijing National Laboratory For Molecular Sciences, Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Jian Liu
- Beijing National Laboratory For Molecular Sciences, Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
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41
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Markthaler D, Zeman J, Baz J, Smiatek J, Hansen N. Validation of Trimethylamine-N-oxide (TMAO) Force Fields Based on Thermophysical Properties of Aqueous TMAO Solutions. J Phys Chem B 2017; 121:10674-10688. [DOI: 10.1021/acs.jpcb.7b07774] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Daniel Markthaler
- Institute of Thermodynamics and Thermal Process Engineering and ‡Institute for Computational
Physics, University of Stuttgart, D-70569 Stuttgart, Germany
| | - Johannes Zeman
- Institute of Thermodynamics and Thermal Process Engineering and ‡Institute for Computational
Physics, University of Stuttgart, D-70569 Stuttgart, Germany
| | - Jörg Baz
- Institute of Thermodynamics and Thermal Process Engineering and ‡Institute for Computational
Physics, University of Stuttgart, D-70569 Stuttgart, Germany
| | - Jens Smiatek
- Institute of Thermodynamics and Thermal Process Engineering and ‡Institute for Computational
Physics, University of Stuttgart, D-70569 Stuttgart, Germany
| | - Niels Hansen
- Institute of Thermodynamics and Thermal Process Engineering and ‡Institute for Computational
Physics, University of Stuttgart, D-70569 Stuttgart, Germany
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42
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Benavides AL, Portillo MA, Chamorro VC, Espinosa JR, Abascal JLF, Vega C. A potential model for sodium chloride solutions based on the TIP4P/2005 water model. J Chem Phys 2017; 147:104501. [DOI: 10.1063/1.5001190] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- A. L. Benavides
- Departamento de Ingeniería Física, División de Ciencias e Ingenierías, Universidad de Guanajuato, Loma del Bosque 103, Col. Lomas del Campestre, CP 37150 León, Mexico
| | - M. A. Portillo
- Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - V. C. Chamorro
- Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - J. R. Espinosa
- Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - J. L. F. Abascal
- Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - C. Vega
- Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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43
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Gonzalez-Salgado D, Vega C. A new intermolecular potential for simulations of methanol: The OPLS/2016 model. J Chem Phys 2017; 145:034508. [PMID: 27448897 DOI: 10.1063/1.4958320] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work, a new rigid-nonpolarizable model of methanol is proposed. The model has three sites, located at the same positions as those used in the OPLS model previously proposed by Jorgensen [J. Phys. Chem. 90, 1276 (1986)]. However, partial charges and the values of the Lennard-Jones parameters were modified by fitting to an adequately selected set of target properties including solid-fluid experimental data. The new model was denoted as OPLS/2016. The overall performance of this model was evaluated and compared to that obtained with other popular models of methanol using a similar test to that recently proposed for water models. In the test, a certain numerical score is given to each model. It was found that the OPLS/2016 obtained the highest score (7.4 of a maximum of 10) followed by L1 (6.6), L2 (6.4), OPLS (5.8), and H1 (3.5) models. The improvement of OPLS/2016 with respect to L1 and L2 is mainly due to an improvement in the description of fluid-solid equilibria (the melting point is only 14 K higher than the experimental value). In addition, it was found that no methanol model was able to reproduce the static dielectric constant and the isobaric heat capacity, whereas the better global performance was found for models that reproduce the vaporization enthalpy once the so-called polarization term is included. Similar conclusions were suggested previously in the analysis of water models and are confirmed here for methanol.
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Affiliation(s)
- D Gonzalez-Salgado
- Departamento de Física Aplicada, Universidad de Vigo, 32004 Ourense, Spain
| | - C Vega
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid, Spain
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44
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Liu H, Wang Y, Bowman JM. Transferable ab Initio Dipole Moment for Water: Three Applications to Bulk Water. J Phys Chem B 2015; 120:1735-42. [DOI: 10.1021/acs.jpcb.5b09213] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hanchao Liu
- Cherry L. Emerson Center
for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Yimin Wang
- Cherry L. Emerson Center
for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Joel M. Bowman
- Cherry L. Emerson Center
for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States
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45
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Medders GR, Paesani F. Infrared and Raman Spectroscopy of Liquid Water through "First-Principles" Many-Body Molecular Dynamics. J Chem Theory Comput 2015; 11:1145-54. [PMID: 26579763 DOI: 10.1021/ct501131j] [Citation(s) in RCA: 161] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Vibrational spectroscopy is a powerful technique to probe the structure and dynamics of water. However, deriving an unambiguous molecular-level interpretation of the experimental spectral features remains a challenge due to the complexity of the underlying hydrogen-bonding network. In this contribution, we present an integrated theoretical and computational framework (named many-body molecular dynamics or MB-MD) that, by systematically removing uncertainties associated with existing approaches, enables a rigorous modeling of vibrational spectra of water from quantum dynamical simulations. Specifically, we extend approaches used to model the many-body expansion of interaction energies to develop many-body representations of the dipole moment and polarizability of water. The combination of these "first-principles" representations with centroid molecular dynamics simulations enables the simulation of infrared and Raman spectra of liquid water under ambient conditions that, without relying on any ad hoc parameters, are in good agreement with the corresponding experimental results. Importantly, since the many-body energy, dipole, and polarizability surfaces employed in the simulations are derived independently from accurate fits to correlated electronic structure data, MB-MD allows for a systematic analysis of the calculated spectra in terms of both electronic and dynamical contributions. The present analysis suggests that, while MB-MD correctly reproduces both the shifts and the shapes of the main spectroscopic features, an improved description of quantum dynamical effects possibly combined with a dissociable water potential may be necessary for a quantitative representation of the OH stretch band.
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Affiliation(s)
- Gregory R Medders
- Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92037, United States
| | - Francesco Paesani
- Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92037, United States
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