1
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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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2
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Bedrov D, Piquemal JP, Borodin O, MacKerell AD, Roux B, Schröder C. Molecular Dynamics Simulations of Ionic Liquids and Electrolytes Using Polarizable Force Fields. Chem Rev 2019; 119:7940-7995. [PMID: 31141351 PMCID: PMC6620131 DOI: 10.1021/acs.chemrev.8b00763] [Citation(s) in RCA: 278] [Impact Index Per Article: 55.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Indexed: 11/30/2022]
Abstract
Many applications in chemistry, biology, and energy storage/conversion research rely on molecular simulations to provide fundamental insight into structural and transport properties of materials with high ionic concentrations. Whether the system is comprised entirely of ions, like ionic liquids, or is a mixture of a polar solvent with a salt, e.g., liquid electrolytes for battery applications, the presence of ions in these materials results in strong local electric fields polarizing solvent molecules and large ions. To predict properties of such systems from molecular simulations often requires either explicit or mean-field inclusion of the influence of polarization on electrostatic interactions. In this manuscript, we review the pros and cons of different treatments of polarization ranging from the mean-field approaches to the most popular explicit polarization models in molecular dynamics simulations of ionic materials. For each method, we discuss their advantages and disadvantages and emphasize key assumptions as well as their adjustable parameters. Strategies for the development of polarizable models are presented with a specific focus on extracting atomic polarizabilities. Finally, we compare simulations using polarizable and nonpolarizable models for several classes of ionic systems, discussing the underlying physics that each approach includes or ignores, implications for implementation and computational efficiency, and the accuracy of properties predicted by these methods compared to experiments.
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Affiliation(s)
- Dmitry Bedrov
- Department
of Materials Science & Engineering, University of Utah, 122 South Central Campus Drive, Room 304, Salt Lake City, Utah 84112, United States
| | - Jean-Philip Piquemal
- Laboratoire
de Chimie Théorique, Sorbonne Université,
UMR 7616 CNRS, CC137, 4 Place Jussieu, Tour 12-13, 4ème étage, 75252 Paris Cedex 05, France
- Institut
Universitaire de France, 75005, Paris Cedex 05, France
- Department
of Biomedical Engineering, The University
of Texas at Austin, Austin, Texas 78712, United States
| | - Oleg Borodin
- Electrochemistry
Branch, Sensors and Electron Devices Directorate, Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20703, United
States
| | - Alexander D. MacKerell
- Department
of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 Penn Street, Baltimore, Maryland 21201, United
States
| | - Benoît Roux
- Department
of Biochemistry and Molecular Biology, Gordon Center for Integrative
Science, University of Chicago, 929 57th Street, Chicago, Illinois 60637, United States
| | - Christian Schröder
- Department
of Computational Biological Chemistry, University
of Vienna, Währinger Strasse 17, A-1090 Vienna, Austria
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3
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Effect of truncating electrostatic interactions on predicting thermodynamic properties of water–methanol systems. MOLECULAR SIMULATION 2018. [DOI: 10.1080/08927022.2018.1547824] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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4
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Jamali SH, Hartkamp R, Bardas C, Söhl J, Vlugt TJH, Moultos OA. Shear Viscosity Computed from the Finite-Size Effects of Self-Diffusivity in Equilibrium Molecular Dynamics. J Chem Theory Comput 2018; 14:5959-5968. [PMID: 30296092 PMCID: PMC6236468 DOI: 10.1021/acs.jctc.8b00625] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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A method is proposed for calculating
the shear viscosity of a liquid
from finite-size effects of self-diffusion coefficients in Molecular
Dynamics simulations. This method uses the difference in the self-diffusivities,
computed from at least two system sizes, and an analytic equation
to calculate the shear viscosity. To enable the efficient use of this
method, a set of guidelines is developed. The most efficient number
of system sizes is two and the large system is at least four times
the small system. The number of independent simulations for each system
size should be assigned in such a way that 50%–70% of the total
available computational resources are allocated to the large system.
We verified the method for
250 binary and 26 ternary Lennard-Jones systems, pure water, and an
ionic liquid ([Bmim][Tf2N]). The computed shear viscosities
are in good agreement with viscosities obtained from equilibrium Molecular
Dynamics simulations for all liquid systems far from the critical
point. Our results indicate that the proposed method is suitable for
multicomponent mixtures and highly viscous liquids. This may enable
the systematic screening of the viscosities of ionic liquids and deep
eutectic solvents.
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Affiliation(s)
- Seyed Hossein Jamali
- Engineering Thermodynamics, Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering , Delft University of Technology , Leeghwaterstraat 39 , 2628CB Delft , The Netherlands
| | - Remco Hartkamp
- Engineering Thermodynamics, Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering , Delft University of Technology , Leeghwaterstraat 39 , 2628CB Delft , The Netherlands
| | - Christos Bardas
- Engineering Thermodynamics, Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering , Delft University of Technology , Leeghwaterstraat 39 , 2628CB Delft , The Netherlands
| | - Jakob Söhl
- Delft Institute of Applied Mathematics , Delft University of Technology , van Mourik Broekmanweg 6 , 2628XE Delft , The Netherlands
| | - Thijs J H Vlugt
- Engineering Thermodynamics, Process & 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 & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering , Delft University of Technology , Leeghwaterstraat 39 , 2628CB Delft , The Netherlands
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5
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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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6
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Unke OT, Devereux M, Meuwly M. Minimal distributed charges: Multipolar quality at the cost of point charge electrostatics. J Chem Phys 2018; 147:161712. [PMID: 29096479 DOI: 10.1063/1.4993424] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Most empirical force fields use atom-centered point charges (PCs) to represent the electrostatic potential (ESP) around molecules. While such PC models are computationally efficient, they are unable to capture anisotropic electronic features, such as σ holes or lone pairs. These features are better described using atomic multipole (MTP) moments, which significantly improve the quality of the resulting ESP. However, the improvement comes at the expense of a considerably increased computational complexity and cost for calculating the interaction energies and forces. In the present work, a novel minimal distributed charge model (MDCM) based on off-centered point charges is presented and the quality of the resulting ESP is compared to the performance of MTPs and atom-centered PC models for several test molecules. All three models are fitted using the same algorithm based on differential evolution, which is available as a Fortran90 program from the authors upon request. We show that the MDCM is capable of approximating the reference ab initio ESP with an accuracy as good as, or better than, MTPs without the need for computationally expensive higher order multipoles. Further it is demonstrated that the MDCM is numerically stable in molecular dynamics simulations and is able to reproduce electrostatic interaction energies and thermodynamic quantities with the same accuracy as MTPs at reduced computational cost.
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Affiliation(s)
- Oliver T Unke
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Mike Devereux
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
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7
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Onufriev AV, Izadi S. Water models for biomolecular simulations. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2017. [DOI: 10.1002/wcms.1347] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Alexey V. Onufriev
- Department of Physics; Virginia Tech; Blacksburg VA USA
- Department of Computer Science; Virginia Tech; Blacksburg VA USA
- Center for Soft Matter and Biological Physics; Virginia Tech; Blacksburg VA USA
| | - Saeed Izadi
- Early Stage Pharmaceutical Development; Genentech Inc.; South San Francisco, CA USA
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8
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Fingerhut BP, Costard R, Elsaesser T. Predominance of short range Coulomb forces in phosphate-water interactions—a theoretical analysis. J Chem Phys 2016. [DOI: 10.1063/1.4962755] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- Benjamin P. Fingerhut
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, D-12489 Berlin, Germany
| | - Rene Costard
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, D-12489 Berlin, Germany
| | - Thomas Elsaesser
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, D-12489 Berlin, Germany
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9
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Schwörer M, Wichmann C, Tavan P. A polarizable QM/MM approach to the molecular dynamics of amide groups solvated in water. J Chem Phys 2016; 144:114504. [PMID: 27004884 DOI: 10.1063/1.4943972] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The infrared (IR) spectra of polypeptides are dominated by the so-called amide bands. Because they originate from the strongly polar and polarizable amide groups (AGs) making up the backbone, their spectral positions sensitively depend on the local electric fields. Aiming at accurate computations of these IR spectra by molecular dynamics (MD) simulations, which derive atomic forces from a hybrid quantum and molecular mechanics (QM/MM) Hamiltonian, here we consider the effects of solvation in bulk liquid water on the amide bands of the AG model compound N-methyl-acetamide (NMA). As QM approach to NMA we choose grid-based density functional theory (DFT). For the surrounding MM water, we develop, largely based on computations, a polarizable molecular mechanics (PMM) model potential called GP6P, which features six Gaussian electrostatic sources (one induced dipole, five static partial charge distributions) and, therefore, avoids spurious distortions of the DFT electron density in hybrid DFT/PMM simulations. Bulk liquid GP6P is shown to have favorable properties at the thermodynamic conditions of the parameterization and beyond. Lennard-Jones (LJ) parameters of the DFT fragment NMA are optimized by comparing radial distribution functions in the surrounding GP6P liquid with reference data obtained from a "first-principles" DFT-MD simulation. Finally, IR spectra of NMA in GP6P water are calculated from extended DFT/PMM-MD trajectories, in which the NMA is treated by three different DFT functionals (BP, BLYP, B3LYP). Method-specific frequency scaling factors are derived from DFT-MD simulations of isolated NMA. The DFT/PMM-MD simulations with GP6P and with the optimized LJ parameters then excellently predict the effects of aqueous solvation and deuteration observed in the IR spectra of NMA. As a result, the methods required to accurately compute such spectra by DFT/PMM-MD also for larger peptides in aqueous solution are now at hand.
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Affiliation(s)
- Magnus Schwörer
- Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians Universität München, Oettingenstr. 67, 80538 München, Germany
| | - Christoph Wichmann
- Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians Universität München, Oettingenstr. 67, 80538 München, Germany
| | - Paul Tavan
- Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians Universität München, Oettingenstr. 67, 80538 München, Germany
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10
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Tran KN, Tan ML, Ichiye T. A single-site multipole model for liquid water. J Chem Phys 2016; 145:034501. [DOI: 10.1063/1.4958621] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Kelly N. Tran
- Department of Chemistry, Georgetown University, Washington, DC 20057, USA
| | - Ming-Liang Tan
- Department of Chemistry, Georgetown University, Washington, DC 20057, USA
| | - Toshiko Ichiye
- Department of Chemistry, Georgetown University, Washington, DC 20057, USA
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11
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Tafipolsky M, Ansorg K. Toward a Physically Motivated Force Field: Hydrogen Bond Directionality from a Symmetry-Adapted Perturbation Theory Perspective. J Chem Theory Comput 2016; 12:1267-79. [DOI: 10.1021/acs.jctc.5b01057] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maxim Tafipolsky
- Institut
für Physikalische
und Theoretische Chemie, Universität Würzburg, Campus
Hubland Nord, Emil-Fischer-Strasse 42, D-97074 Würzburg, Germany
| | - Kay Ansorg
- Institut
für Physikalische
und Theoretische Chemie, Universität Würzburg, Campus
Hubland Nord, Emil-Fischer-Strasse 42, D-97074 Würzburg, Germany
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12
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Hamm P. 2D-Raman-THz spectroscopy: a sensitive test of polarizable water models. J Chem Phys 2015; 141:184201. [PMID: 25399140 DOI: 10.1063/1.4901216] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In a recent paper, the experimental 2D-Raman-THz response of liquid water at ambient conditions has been presented [J. Savolainen, S. Ahmed, and P. Hamm, Proc. Natl. Acad. Sci. U. S. A. 110, 20402 (2013)]. Here, all-atom molecular dynamics simulations are performed with the goal to reproduce the experimental results. To that end, the molecular response functions are calculated in a first step, and are then convoluted with the laser pulses in order to enable a direct comparison with the experimental results. The molecular dynamics simulation are performed with several different water models: TIP4P/2005, SWM4-NDP, and TL4P. As polarizability is essential to describe the 2D-Raman-THz response, the TIP4P/2005 water molecules are amended with either an isotropic or a anisotropic polarizability a posteriori after the molecular dynamics simulation. In contrast, SWM4-NDP and TL4P are intrinsically polarizable, and hence the 2D-Raman-THz response can be calculated in a self-consistent way, using the same force field as during the molecular dynamics simulation. It is found that the 2D-Raman-THz response depends extremely sensitively on details of the water model, and in particular on details of the description of polarizability. Despite the limited time resolution of the experiment, it could easily distinguish between various water models. Albeit not perfect, the overall best agreement with the experimental data is obtained for the TL4P water model.
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Affiliation(s)
- Peter Hamm
- Department of Chemistry, University of Zurich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland
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13
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Tainter CJ, Shi L, Skinner JL. Reparametrized E3B (Explicit Three-Body) Water Model Using the TIP4P/2005 Model as a Reference. J Chem Theory Comput 2015; 11:2268-77. [DOI: 10.1021/acs.jctc.5b00117] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Craig J. Tainter
- Theoretical Chemistry Institute
and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Liang Shi
- Theoretical Chemistry Institute
and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - James L. Skinner
- Theoretical Chemistry Institute
and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
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14
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Schwörer M, Lorenzen K, Mathias G, Tavan P. Utilizing fast multipole expansions for efficient and accurate quantum-classical molecular dynamics simulations. J Chem Phys 2015; 142:104108. [PMID: 25770527 DOI: 10.1063/1.4914329] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Recently, a novel approach to hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulations has been suggested [Schwörer et al., J. Chem. Phys. 138, 244103 (2013)]. Here, the forces acting on the atoms are calculated by grid-based density functional theory (DFT) for a solute molecule and by a polarizable molecular mechanics (PMM) force field for a large solvent environment composed of several 10(3)-10(5) molecules as negative gradients of a DFT/PMM hybrid Hamiltonian. The electrostatic interactions are efficiently described by a hierarchical fast multipole method (FMM). Adopting recent progress of this FMM technique [Lorenzen et al., J. Chem. Theory Comput. 10, 3244 (2014)], which particularly entails a strictly linear scaling of the computational effort with the system size, and adapting this revised FMM approach to the computation of the interactions between the DFT and PMM fragments of a simulation system, here, we show how one can further enhance the efficiency and accuracy of such DFT/PMM-MD simulations. The resulting gain of total performance, as measured for alanine dipeptide (DFT) embedded in water (PMM) by the product of the gains in efficiency and accuracy, amounts to about one order of magnitude. We also demonstrate that the jointly parallelized implementation of the DFT and PMM-MD parts of the computation enables the efficient use of high-performance computing systems. The associated software is available online.
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Affiliation(s)
- Magnus Schwörer
- Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians Universität München, Oettingenstr. 67, 80538 München, Germany
| | - Konstantin Lorenzen
- Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians Universität München, Oettingenstr. 67, 80538 München, Germany
| | - Gerald Mathias
- Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians Universität München, Oettingenstr. 67, 80538 München, Germany
| | - Paul Tavan
- Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians Universität München, Oettingenstr. 67, 80538 München, Germany
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15
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16
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Tan ML, Cendagorta JR, Ichiye T. The molecular charge distribution, the hydration shell, and the unique properties of liquid water. J Chem Phys 2014; 141:244504. [DOI: 10.1063/1.4904263] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ming-Liang Tan
- Department of Chemistry, Georgetown University, Washington DC 20057, USA
| | | | - Toshiko Ichiye
- Department of Chemistry, Georgetown University, Washington DC 20057, USA
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17
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Devereux M, Raghunathan S, Fedorov DG, Meuwly M. A Novel, Computationally Efficient Multipolar Model Employing Distributed Charges for Molecular Dynamics Simulations. J Chem Theory Comput 2014; 10:4229-41. [PMID: 26588121 DOI: 10.1021/ct500511t] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
A truncated multipole expansion can be re-expressed exactly using an appropriate arrangement of point charges. This means that groups of point charges that are shifted away from nuclear coordinates can be used to achieve accurate electrostatics for molecular systems. We introduce a multipolar electrostatic model formulated in this way for use in computationally efficient multipolar molecular dynamics simulations with well-defined forces and energy conservation in NVE (constant number-volume-energy) simulations. A framework is introduced to distribute torques arising from multipole moments throughout a molecule, and a refined fitting approach is suggested to obtain atomic multipole moments that are optimized for accuracy and numerical stability in a force field context. The formulation of the charge model is outlined as it has been implemented into CHARMM, with application to test systems involving H2O and chlorobenzene. As well as ease of implementation and computational efficiency, the approach can be used to provide snapshots for multipolar QM/MM calculations in QM/MM-MD studies and easily combined with a standard point-charge force field to allow mixed multipolar/point charge simulations of large systems.
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Affiliation(s)
- Mike Devereux
- Universität Basel , Departement Chemie, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Shampa Raghunathan
- Universität Basel , Departement Chemie, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Dmitri G Fedorov
- NRI, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
| | - Markus Meuwly
- Universität Basel , Departement Chemie, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
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18
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Lorenzen K, Wichmann C, Tavan P. Including the Dispersion Attraction into Structure-Adapted Fast Multipole Expansions for MD Simulations. J Chem Theory Comput 2014; 10:3244-59. [DOI: 10.1021/ct500319a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Konstantin Lorenzen
- Lehrstuhl
für Biomolekulare
Optik, Ludwig-Maximilians-Universität, Oettingenstr. 67, 80538 München, Germany
| | - Christoph Wichmann
- Lehrstuhl
für Biomolekulare
Optik, Ludwig-Maximilians-Universität, Oettingenstr. 67, 80538 München, Germany
| | - Paul Tavan
- Lehrstuhl
für Biomolekulare
Optik, Ludwig-Maximilians-Universität, Oettingenstr. 67, 80538 München, Germany
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