1
|
Chen X, Liu M, Gao J. CARNOT: a Fragment-Based Direct Molecular Dynamics and Virtual-Reality Simulation Package for Reactive Systems. J Chem Theory Comput 2022; 18:1297-1313. [PMID: 35129348 DOI: 10.1021/acs.jctc.1c01032] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Traditionally, the study of reaction mechanisms of complex reaction systems such as combustion has been performed on an individual basis by optimizations of transition structure and minimum energy path or by reaction dynamics trajectory calculations for one elementary reaction at a time. It is effective, but time-consuming, whereas important and unexpected processes could have been missed. In this article, we present a direct molecular dynamics (DMD) approach and a virtual-reality simulation program, CARNOT, in which plausible chemical reactions are simulated simultaneously at finite temperature and pressure conditions. A key concept of the present ab initio molecular dynamics method is to partition a large, chemically reactive system into molecular fragments that can be adjusted on the fly of a DMD simulation. The theory represents an extension of the explicit polarization method to reactive events, called ReX-Pol. We propose a highest-and-lowest adapted-spin approximation to define the local spins of individual fragments, rather than treating the entire system by a delocalized wave function. Consequently, the present ab initio DMD can be applied to reactive systems consisting of an arbitrarily varying number of closed and open-shell fragments such as free radicals, zwitterions, and separate ions found in combustion and other reactions. A graph-data structure algorithm was incorporated in CARNOT for the analysis of reaction networks, suitable for reaction mechanism reduction. Employing the PW91 density functional theory and the 6-31+G(d) basis set, the capabilities of the CARNOT program were illustrated by a combustion reaction, consisting of 28 650 atoms, and by reaction network analysis that revealed a range of mechanistic and dynamical events. The method may be useful for applications to other types of complex reactions.
Collapse
Affiliation(s)
- Xin Chen
- Peking University Shenzhen Graduate School, Shenzhen, Guangdong 581055, China.,Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen, Guangdong 581055, China
| | - Meiyi Liu
- Peking University Shenzhen Graduate School, Shenzhen, Guangdong 581055, China.,Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen, Guangdong 581055, China
| | - Jiali Gao
- Peking University Shenzhen Graduate School, Shenzhen, Guangdong 581055, China.,Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen, Guangdong 581055, China.,Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, United States
| |
Collapse
|
2
|
Kim B, Shao Y, Pu J. Doubly Polarized QM/MM with Machine Learning Chaperone Polarizability. J Chem Theory Comput 2021; 17:7682-7695. [PMID: 34723536 PMCID: PMC9047028 DOI: 10.1021/acs.jctc.1c00567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A major shortcoming of semiempirical (SE) molecular orbital methods is their severe underestimation of molecular polarizability compared with experimental and ab initio (AI) benchmark data. In a combined quantum mechanical and molecular mechanical (QM/MM) treatment of solution-phase reactions, solute described by SE methods therefore tends to generate inadequate electronic polarization response to solvent electric fields, which often leads to large errors in free energy profiles. To address this problem, here we present a hybrid framework that improves the response property of SE/MM methods through high-level molecular-polarizability fitting. Specifically, we place on QM atoms a set of corrective polarizabilities (referred to as chaperone polarizabilities), whose magnitudes are determined from machine learning (ML) to reproduce the condensed-phase AI molecular polarizability along the minimum free energy path. These chaperone polarizabilities are then used in a machinery similar to a polarizable force field calculation to compensate for the missing polarization energy in the conventional SE/MM simulations. Because QM atoms in this treatment host SE wave functions as well as classical polarizabilities, both polarized by MM electric fields, we name this method doubly polarized QM/MM (dp-QM/MM). We demonstrate the new method on the free energy simulations of the Menshutkin reaction in water. Using AM1/MM as a base method, we show that ML chaperones greatly reduce the error in the solute molecular polarizability from 6.78 to 0.03 Å3 with respect to the density functional theory benchmark. The chaperone correction leads to ∼10 kcal/mol of additional polarization energy in the product region, bringing the simulated free energy profiles to closer agreement with the experimental results. Furthermore, the solute-solvent radial distribution functions show that the chaperone polarizabilities modify the free energy profiles through enhanced solvation corrections when the system evolves from the charge-neutral reactant state to the charge-separated transition and product states. These results suggest that the dp-QM/MM method, enabled by ML chaperone polarizabilities, provides a very physical remedy for the underpolarization problem in SE/MM-based free energy simulations.
Collapse
Affiliation(s)
- Bryant Kim
- Department of Chemistry and Chemical Biology,
Indiana University-Purdue University Indianapolis, 402 N. Blackford St.,
Indianapolis, IN 46202
| | - Yihan Shao
- Department of Chemistry and Biochemistry, University
of Oklahoma, 101 Stephenson Pkwy, Norman, OK 73019,Correspondence:
and
| | - Jingzhi Pu
- Department of Chemistry and Chemical Biology,
Indiana University-Purdue University Indianapolis, 402 N. Blackford St.,
Indianapolis, IN 46202,Correspondence:
and
| |
Collapse
|
3
|
Ge Y, Huang S, Hu Y, Zhang L, He L, Krajewski S, Ortiz M, Jin Y, Zhang W. Highly active alkyne metathesis catalysts operating under open air condition. Nat Commun 2021; 12:1136. [PMID: 33602910 PMCID: PMC7893043 DOI: 10.1038/s41467-021-21364-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 01/21/2021] [Indexed: 01/17/2023] Open
Abstract
Alkyne metathesis represents a rapidly emerging synthetic method that has shown great potential in small molecule and polymer synthesis. However, its practical use has been impeded by the limited availability of user-friendly catalysts and their generally high moisture/air sensitivity. Herein, we report an alkyne metathesis catalyst system that can operate under open-air conditions with a broad substrate scope and excellent yields. These catalysts are composed of simple multidentate tris(2-hydroxyphenyl)methane ligands, which can be easily prepared in multi-gram scale. The catalyst substituted with electron withdrawing cyano groups exhibits the highest activity at room temperature with excellent functional group tolerance (-OH, -CHO, -NO2, pyridyl). More importantly, the catalyst provides excellent yields (typically >90%) in open air, comparable to those operating under argon. When dispersed in paraffin wax, the active catalyst can be stored on a benchtop under ambient conditions without any decrease in activity for one day (retain 88% after 3 days). This work opens many possibilities for developing highly active user-friendly alkyne metathesis catalysts that can function in open air. Alkyne metathesis catalysts usually suffer from high moisture/air sensitivity, which limit their wide applicability. Here, the authors report efficient alkyne metathesis catalysts that can operate under open-air conditions with a broad functional group tolerance.
Collapse
Affiliation(s)
- Yanqing Ge
- School of Chemistry and Pharmaceutical Engineering, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China.,Department of Chemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Shaofeng Huang
- Department of Chemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Yiming Hu
- Department of Chemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Lei Zhang
- College of Chemistry, Sichuan University, Chengdu, China
| | - Ling He
- College of Chemistry, Sichuan University, Chengdu, China
| | | | - Michael Ortiz
- Department of Chemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Yinghua Jin
- Department of Chemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Wei Zhang
- Department of Chemistry, University of Colorado Boulder, Boulder, CO, USA.
| |
Collapse
|
4
|
Chen X, Qu Z, Suo B, Gao J. A self-consistent coulomb bath model using density fitting. J Comput Chem 2020; 41:1698-1708. [PMID: 32369627 DOI: 10.1002/jcc.26211] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 03/02/2020] [Accepted: 04/05/2020] [Indexed: 12/24/2022]
Abstract
A self-consistent Coulomb bath model is presented to provide an accurate and efficient way of performing calculations for interfragment electrostatic and polarization interactions. In this method, a condensed-phase system is partitioned into molecular fragment blocks. Each fragment is embedded in the Coulomb bath due to other fragments. Importantly, the present Coulomb bath is represented using a density fitting method in which the electron densities of molecular fragments are fitted using an atom-centered auxiliary basis set of Gaussian type. The Coulomb bath is incorporated into an effective Hamiltonian for each fragment, with which the electron density is optimized through an iterative double self-consistent field (DSCF) procedure to realize the mutual many-body polarization effects. In this work, the accuracy of interfragment interaction energies enumerated using the Coulomb bath is tested, showing a good agreement with the exact results from an energy decomposition analysis. The qualitative features of many-body polarization effects are visualized by electron density difference plots. It is also shown that the present DSCF method can yield fast and robust convergence with near-linear scaling in performance with increase in system size.
Collapse
Affiliation(s)
- Xin Chen
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China.,Shenzhen Bay Laboratory, Shenzhen, China
| | - Zexing Qu
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, China
| | - Bingbing Suo
- Shaanxi Key Laboratory for Theoretical Physics Frontiers, Institute of Modern Physics, Northwest University, Xi'an, Shaanxi, China
| | - Jiali Gao
- Shenzhen Bay Laboratory, Shenzhen, China.,Laboratory of Computational Chemistry and Drug Design, Peking University Shenzhen Graduate School, Shenzhen, China.,Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota, USA
| |
Collapse
|
5
|
Wang X, Gao J. Atomic partial charge predictions for furanoses by random forest regression with atom type symmetry function. RSC Adv 2020; 10:666-673. [PMID: 35494472 PMCID: PMC9048215 DOI: 10.1039/c9ra09337k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Accepted: 12/18/2019] [Indexed: 01/04/2023] Open
Abstract
Furanoses that are components for many important biomolecules have complicated conformational spaces due to the flexible ring and exo-cyclic moieties. Machine learning algorithms, which require descriptors as structural inputs, can be used to efficiently compute conformational adaptive (CA) charges to capture the electrostatic potential variations caused by the conformational changes in the molecular mechanics (MM) calculations. In the present study, we introduced atom type symmetry function (ATSF) developed based on atom centered symmetry function (ACSF) for describing conformations for furanoses, in which atoms were categorized by atom types defined by their properties or connectivity in classic molecular mechanics (MM) force field parameters to generate a suitable coordinate size. Random forest regression (RFR) models with ATSF showed improvements for predicting CA charges and dipole moments for furanoses compared to those with ACSF and atom name symmetry functions where atoms were categorized by their unique atom names. The CA charges predicted by RFR models with ATSF showed more comparable reproductions of the carbohydrate-water and carbohydrate-protein interactions computed with RESP charges individually derived from QM calculations than the ensemble-averaged atomic charge sets commonly employed in molecular mechanics force fields, suggesting that the predicted CA charges were capable of including electrostatic variations in their dynamic charge values. Improvements by ATSF showed that categorizing atoms by atom types introduced chemical structural perceptions to descriptors and produced a suitable coordinate size in ATSF to capture key structural features for furanoses. This categorizing scheme also allows ATSF to be readily adopted by other biomolecules thanks to the broad implementations of MM force fields.
Collapse
Affiliation(s)
- Xiaocong Wang
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Informatics, Huazhong Agricultural University Wuhan China
| | - Jun Gao
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Informatics, Huazhong Agricultural University Wuhan China
| |
Collapse
|
6
|
Dubbeldam D, Walton KS, Vlugt TJH, Calero S. Design, Parameterization, and Implementation of Atomic Force Fields for Adsorption in Nanoporous Materials. ADVANCED THEORY AND SIMULATIONS 2019. [DOI: 10.1002/adts.201900135] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- David Dubbeldam
- Van 't Hoff Institute for Molecular SciencesUniversity of AmsterdamScience Park 904 1098XH Amsterdam The Netherlands
| | - Krista S. Walton
- School of Chemical & Biomolecular EngineeringGeorgia Institute of Technology311 Ferst Dr. NW Atlanta GA 30332‐0100 USA
| | - Thijs J. H. Vlugt
- Delft University of TechnologyProcess & Energy DepartmentLeeghwaterstraat 39 2628CB Delft The Netherlands
| | - Sofia Calero
- Department of PhysicalChemical and Natural SystemsUniversity Pablo de OlavideSevilla 41013 Spain
| |
Collapse
|
7
|
Hou S, Qureshi AH, Wei Z. Atomic Charges in Highly Ionic Diatomic Molecules. ACS OMEGA 2018; 3:17180-17187. [PMID: 31458337 PMCID: PMC6643469 DOI: 10.1021/acsomega.8b02370] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 11/27/2018] [Indexed: 06/10/2023]
Abstract
Atomic charges were investigated as functions of detectable atomic and molecular constants at equilibrium structures. It was found based upon the variation idea that atomic charges in highly ionic molecules can be expressed as a function of molecular dipole moments, polarizabilities of free cations, and polarizabilities of free neutral atoms of the corresponding anions. The function can be given in the form of classical Rittner's relationship (J. Chem. Phys. 1951, 19, 1030). For the ground states of alkali halide molecules, the predicted atomic charges are close to an elementary charge e and the predicted dipole moments are in good agreement with the observed values; for spin-restricted high-ionic systems such as the lowest 9Σ electronic states of BN, AlN, GaN, BP, AlP, GaP, BAs, AlAs, and GaAs molecules, the predicted atomic charges are also near 1e and in good agreement with the results of natural population analysis at MRCI/cc-pvqz and HF/6-311+G(3df) levels. Polarizabilities for the lowest quintet states of B-, Al-, Ga-, N+, P+, and As+ ions were also obtained based upon high-level ab initio computations. Atomic charges from other related methods are also investigated for comparison. The results demonstrate that high-quality atomic charges can be obtained with detectable variables, such as molecular dipole moment, vibrational frequency, as well as polarizabilities of the related free atoms and ions.
Collapse
Affiliation(s)
- Shilin Hou
- E-mail: .
Phone: 86-532-6678 6562 (S.H.)
| | | | | |
Collapse
|
8
|
Milne AW, Jorge M. Polarization Corrections and the Hydration Free Energy of Water. J Chem Theory Comput 2018; 15:1065-1078. [DOI: 10.1021/acs.jctc.8b01115] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Andrew W. Milne
- Department of Chemical and Process Engineering, University of Strathclyde, Glasgow G1 1XQ, United Kingdom
| | - Miguel Jorge
- Department of Chemical and Process Engineering, University of Strathclyde, Glasgow G1 1XQ, United Kingdom
| |
Collapse
|
9
|
Abstract
Complex carbohydrates are ubiquitous in nature, and together with proteins and nucleic acids they comprise the building blocks of life. But unlike proteins and nucleic acids, carbohydrates form nonlinear polymers, and they are not characterized by robust secondary or tertiary structures but rather by distributions of well-defined conformational states. Their molecular flexibility means that oligosaccharides are often refractory to crystallization, and nuclear magnetic resonance (NMR) spectroscopy augmented by molecular dynamics (MD) simulation is the leading method for their characterization in solution. The biological importance of carbohydrate-protein interactions, in organismal development as well as in disease, places urgency on the creation of innovative experimental and theoretical methods that can predict the specificity of such interactions and quantify their strengths. Additionally, the emerging realization that protein glycosylation impacts protein function and immunogenicity places the ability to define the mechanisms by which glycosylation impacts these features at the forefront of carbohydrate modeling. This review will discuss the relevant theoretical approaches to studying the three-dimensional structures of this fascinating class of molecules and interactions, with reference to the relevant experimental data and techniques that are key for validation of the theoretical predictions.
Collapse
Affiliation(s)
- Robert J Woods
- Complex Carbohydrate Research Center and Department of Biochemistry and Molecular Biology , University of Georgia , 315 Riverbend Road , Athens , Georgia 30602 , United States
| |
Collapse
|
10
|
Kulik HJ. Large-scale QM/MM free energy simulations of enzyme catalysis reveal the influence of charge transfer. Phys Chem Chem Phys 2018; 20:20650-20660. [PMID: 30059109 PMCID: PMC6085747 DOI: 10.1039/c8cp03871f] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Hybrid quantum mechanical-molecular mechanical (QM/MM) simulations provide key insights into enzyme structure-function relationships. Numerous studies have demonstrated that large QM regions are needed to systematically converge ground state, zero temperature properties with electrostatic embedding QM/MM. However, it is not well known if ab initio QM/MM free energy simulations have this same dependence, in part due to the hundreds of thousands of energy evaluations required for free energy estimations that in turn limit QM region size. Here, we leverage recent advances in electronic structure efficiency and accuracy to carry out range-separated hybrid density functional theory free energy simulations in a representative methyltransferase. By studying 200 ps of ab initio QM/MM dynamics for each of five QM regions from minimal (64 atoms) to one-sixth of the protein (544 atoms), we identify critical differences between large and small QM region QM/MM in charge transfer between substrates and active site residues as well as in geometric structure and dynamics that coincide with differences in predicted free energy barriers. Distinct geometric and electronic structure features in the largest QM region indicate that important aspects of enzymatic rate enhancement in methyltransferases are identified with large-scale electronic structure.
Collapse
Affiliation(s)
- Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| |
Collapse
|
11
|
Huang J, Mei Y, König G, Simmonett AC, Pickard FC, Wu Q, Wang LP, MacKerell AD, Brooks BR, Shao Y. An Estimation of Hybrid Quantum Mechanical Molecular Mechanical Polarization Energies for Small Molecules Using Polarizable Force-Field Approaches. J Chem Theory Comput 2017; 13:679-695. [PMID: 28081366 DOI: 10.1021/acs.jctc.6b01125] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, we report two polarizable molecular mechanics (polMM) force field models for estimating the polarization energy in hybrid quantum mechanical molecular mechanical (QM/MM) calculations. These two models, named the potential of atomic charges (PAC) and potential of atomic dipoles (PAD), are formulated from the ab initio quantum mechanical (QM) response kernels for the prediction of the QM density response to an external molecular mechanical (MM) environment (as described by external point charges). The PAC model is similar to fluctuating charge (FQ) models because the energy depends on external electrostatic potential values at QM atomic sites; the PAD energy depends on external electrostatic field values at QM atomic sites, resembling induced dipole (ID) models. To demonstrate their uses, we apply the PAC and PAD models to 12 small molecules, which are solvated by TIP3P water. The PAC model reproduces the QM/MM polarization energy with a R2 value of 0.71 for aniline (in 10,000 TIP3P water configurations) and 0.87 or higher for other 11 solute molecules, while the PAD model has a much better performance with R2 values of 0.98 or higher. The PAC model reproduces reference QM/MM hydration free energies for 12 solute molecules with a RMSD of 0.59 kcal/mol. The PAD model is even more accurate, with a much smaller RMSD of 0.12 kcal/mol, with respect to the reference. This suggests that polarization effects, including both local charge distortion and intramolecular charge transfer, can be well captured by induced dipole type models with proper parametrization.
Collapse
Affiliation(s)
- Jing Huang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland , 20 Penn Street, Baltimore, Maryland 21201, United States.,Laboratory of Computational Biology, National Institutes of Health, National Heart, Lung and Blood Institute , 5635 Fishers Lane, T-900 Suite, Rockville, Maryland 20852, United States
| | - Ye Mei
- State Key Laboratory of Precision Spectroscopy, School of Physics and Materials Science, East China Normal University , Shanghai 200062, China.,NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, China
| | - Gerhard König
- Max-Planck-Institut für Kohlenforschung , 45470 Mülheim an der Ruhr, NRW Germany, EU
| | - Andrew C Simmonett
- Laboratory of Computational Biology, National Institutes of Health, National Heart, Lung and Blood Institute , 5635 Fishers Lane, T-900 Suite, Rockville, Maryland 20852, United States
| | - Frank C Pickard
- Laboratory of Computational Biology, National Institutes of Health, National Heart, Lung and Blood Institute , 5635 Fishers Lane, T-900 Suite, Rockville, Maryland 20852, United States
| | - Qin Wu
- Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States
| | - Lee-Ping Wang
- Department of Chemistry, University of California , 1 Shields Avenue, Davis, California 95616, United States
| | - Alexander D MacKerell
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland , 20 Penn Street, Baltimore, Maryland 21201, United States
| | - Bernard R Brooks
- Laboratory of Computational Biology, National Institutes of Health, National Heart, Lung and Blood Institute , 5635 Fishers Lane, T-900 Suite, Rockville, Maryland 20852, United States
| | - Yihan Shao
- Q-Chem Inc., 6601 Owens Drive, Suite 105, Pleasanton, California 94588, United States.,Department of Chemistry and Biochemistry, University of Oklahoma , Norman, Oklahoma 73019, United States
| |
Collapse
|
12
|
Fletcher TL, Popelier PLA. Multipolar Electrostatic Energy Prediction for all 20 Natural Amino Acids Using Kriging Machine Learning. J Chem Theory Comput 2016; 12:2742-51. [DOI: 10.1021/acs.jctc.6b00457] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Timothy L. Fletcher
- Manchester Institute of Biotechnology (MIB), 131 Princess Street, Manchester M1 7DN, Great Britain
- School
of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, Great Britain
| | - Paul L. A. Popelier
- Manchester Institute of Biotechnology (MIB), 131 Princess Street, Manchester M1 7DN, Great Britain
- School
of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, Great Britain
| |
Collapse
|
13
|
Jakobsen S, Jensen F. Systematic Improvement of Potential-Derived Atomic Multipoles and Redundancy of the Electrostatic Parameter Space. J Chem Theory Comput 2015; 10:5493-504. [PMID: 26583232 DOI: 10.1021/ct500803r] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We assess the accuracy of force field (FF) electrostatics at several levels of approximation from the standard model using fixed partial charges to conformational specific multipole fits including up to quadrupole moments. Potential-derived point charges and multipoles are calculated using least-squares methods for a total of ∼1000 different conformations of the 20 natural amino acids. Opposed to standard charge fitting schemes the procedure presented in the current work employs fitting points placed on a single isodensity surface, since the electrostatic potential (ESP) on such a surface determines the ESP at all points outside this surface. We find that the effect of multipoles beyond partial atomic charges is of the same magnitude as the effect due to neglecting conformational dependency (i.e., polarizability), suggesting that the two effects should be included at the same level in FF development. The redundancy at both the partial charge and multipole levels of approximation is quantified. We present an algorithm which stepwise reduces or increases the dimensionality of the charge or multipole parameter space and provides an upper limit of the ESP error that can be obtained at a given truncation level. Thereby, we can identify a reduced set of multipole moments corresponding to ∼40% of the total number of multipoles. This subset of parameters provides a significant improvement in the representation of the ESP compared to the simple point charge model and close to the accuracy obtained using the complete multipole parameter space. The selection of the ∼40% most important multipole sites is highly transferable among different conformations, and we find that quadrupoles are of high importance for atoms involved in π-bonding, since the anisotropic electric field generated in such regions requires a large degree of flexibility.
Collapse
Affiliation(s)
- Sofie Jakobsen
- Department of Chemistry, Aarhus University , DK-8000 Aarhus, Denmark
| | - Frank Jensen
- Department of Chemistry, Aarhus University , DK-8000 Aarhus, Denmark
| |
Collapse
|
14
|
Gabrieli A, Sant M, Demontis P, Suffritti GB. Partial Charges in Periodic Systems: Improving Electrostatic Potential (ESP) Fitting via Total Dipole Fluctuations and Multiframe Approaches. J Chem Theory Comput 2015; 11:3829-43. [DOI: 10.1021/acs.jctc.5b00503] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Andrea Gabrieli
- Dipartimento di Chimica e
Farmacia, Università degli Studi di Sassari, Via Vienna
2, 07100 Sassari, Italy
| | - Marco Sant
- Dipartimento di Chimica e
Farmacia, Università degli Studi di Sassari, Via Vienna
2, 07100 Sassari, Italy
| | - Pierfranco Demontis
- Dipartimento di Chimica e
Farmacia, Università degli Studi di Sassari, Via Vienna
2, 07100 Sassari, Italy
| | - Giuseppe B. Suffritti
- Dipartimento di Chimica e
Farmacia, Università degli Studi di Sassari, Via Vienna
2, 07100 Sassari, Italy
| |
Collapse
|
15
|
Mazack MJM, Gao J. Quantum mechanical force field for hydrogen fluoride with explicit electronic polarization. J Chem Phys 2015; 140:204501. [PMID: 24880295 DOI: 10.1063/1.4875922] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The explicit polarization (X-Pol) theory is a fragment-based quantum chemical method that explicitly models the internal electronic polarization and intermolecular interactions of a chemical system. X-Pol theory provides a framework to construct a quantum mechanical force field, which we have extended to liquid hydrogen fluoride (HF) in this work. The parameterization, called XPHF, is built upon the same formalism introduced for the XP3P model of liquid water, which is based on the polarized molecular orbital (PMO) semiempirical quantum chemistry method and the dipole-preserving polarization consistent point charge model. We introduce a fluorine parameter set for PMO, and find good agreement for various gas-phase results of small HF clusters compared to experiments and ab initio calculations at the M06-2X/MG3S level of theory. In addition, the XPHF model shows reasonable agreement with experiments for a variety of structural and thermodynamic properties in the liquid state, including radial distribution functions, interaction energies, diffusion coefficients, and densities at various state points.
Collapse
Affiliation(s)
- Michael J M Mazack
- Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant Street, SE, Minneapolis, Minnesota 55455-0431, USA
| | - Jiali Gao
- Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant Street, SE, Minneapolis, Minnesota 55455-0431, USA
| |
Collapse
|
16
|
Gao J, Truhlar DG, Wang Y, Mazack MJM, Löffler P, Provorse MR, Rehak P. Explicit polarization: a quantum mechanical framework for developing next generation force fields. Acc Chem Res 2014; 47:2837-45. [PMID: 25098651 PMCID: PMC4165456 DOI: 10.1021/ar5002186] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
![]()
Molecular mechanical force fields have been successfully used to
model condensed-phase and biological systems for a half century. By
means of careful parametrization, such classical force fields can
be used to provide useful interpretations of experimental findings
and predictions of certain properties. Yet, there is a need to further
improve computational accuracy for the quantitative prediction of
biomolecular interactions and to model properties that depend on the
wave functions and not just the energy terms. A new strategy called
explicit polarization (X-Pol) has been developed to construct the
potential energy surface and wave functions for macromolecular and
liquid-phase simulations on the basis of quantum mechanics rather
than only using quantum mechanical results to fit analytic force fields.
In this spirit, this approach is called a quantum mechanical force
field (QMFF). X-Pol is a general fragment method for electronic
structure calculations
based on the partition of a condensed-phase or macromolecular system
into subsystems (“fragments”) to achieve computational
efficiency. Here, intrafragment energy and the mutual electronic polarization
of interfragment interactions are treated explicitly using quantum
mechanics. X-Pol can be used as a general, multilevel electronic structure
model for macromolecular systems, and it can also serve as a new-generation
force field. As a quantum chemical model, a variational many-body
(VMB) expansion approach is used to systematically improve interfragment
interactions, including exchange repulsion, charge delocalization,
dispersion, and other correlation energies. As a quantum mechanical
force field, these energy terms are approximated by empirical functions
in the spirit of conventional molecular mechanics. This Account first
reviews the formulation of X-Pol, in the full variationally correct
version, in the faster embedded version, and with systematic many-body
improvements. We discuss illustrative examples involving water clusters
(which show the power of two-body corrections), ethylmethylimidazolium
acetate ionic liquids (which reveal that the amount of charge transfer
between anion and cation is much smaller than what has been assumed
in some classical simulations), and a solvated protein in aqueous
solution (which shows that the average charge distribution of carbonyl
groups along the polypeptide chain depends strongly on their position
in the sequence, whereas they are fixed in most classical force fields).
The development of QMFFs also offers an opportunity to extend the
accuracy of biochemical simulations to areas where classical force
fields are often insufficient, especially in the areas of spectroscopy,
reactivity, and enzyme catalysis.
Collapse
Affiliation(s)
- Jiali Gao
- Theoretical
Chemistry Institute, State Key Laboratory of Theoretical and Computational
Chemistry, Jilin University, Changchun, Jilin Province 130028, People’s Republic of China
- Department
of Chemistry and Supercomputing Institute University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Donald G. Truhlar
- Department
of Chemistry and Supercomputing Institute University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Yingjie Wang
- Department
of Chemistry and Supercomputing Institute University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Michael J. M. Mazack
- Department
of Chemistry and Supercomputing Institute University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Patrick Löffler
- Department
of Chemistry and Supercomputing Institute University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Makenzie R. Provorse
- Department
of Chemistry and Supercomputing Institute University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Pavel Rehak
- Department
of Chemistry and Supercomputing Institute University of Minnesota, Minneapolis, Minnesota 55455, United States
| |
Collapse
|
17
|
Balamurugan D, Aquino AJA, de Dios F, Flores L, Lischka H, Cheung MS. Multiscale Simulation of the Ground and Photo-Induced Charge-Separated States of a Molecular Triad in Polar Organic Solvent: Exploring the Conformations, Fluctuations, and Free Energy Landscapes. J Phys Chem B 2013; 117:12065-75. [DOI: 10.1021/jp4026927] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- D. Balamurugan
- Department
of Physics, University of Houston, Houston, Texas 77204, United States
| | - Adelia J. A. Aquino
- Department
of Chemistry, Texas Tech University, Lubbock, Texas 79409, United States
| | - Francis de Dios
- Department
of Physics, University of Houston, Houston, Texas 77204, United States
| | - Lionel Flores
- Department
of Physics, University of Houston, Houston, Texas 77204, United States
| | - Hans Lischka
- Department
of Chemistry, Texas Tech University, Lubbock, Texas 79409, United States
| | - Margaret S. Cheung
- Department
of Physics, University of Houston, Houston, Texas 77204, United States
| |
Collapse
|
18
|
Han J, Mazack MJM, Zhang P, Truhlar DG, Gao J. Quantum mechanical force field for water with explicit electronic polarization. J Chem Phys 2013; 139:054503. [PMID: 23927266 PMCID: PMC3747793 DOI: 10.1063/1.4816280] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 07/08/2013] [Indexed: 11/14/2022] Open
Abstract
A quantum mechanical force field (QMFF) for water is described. Unlike traditional approaches that use quantum mechanical results and experimental data to parameterize empirical potential energy functions, the present QMFF uses a quantum mechanical framework to represent intramolecular and intermolecular interactions in an entire condensed-phase system. In particular, the internal energy terms used in molecular mechanics are replaced by a quantum mechanical formalism that naturally includes electronic polarization due to intermolecular interactions and its effects on the force constants of the intramolecular force field. As a quantum mechanical force field, both intermolecular interactions and the Hamiltonian describing the individual molecular fragments can be parameterized to strive for accuracy and computational efficiency. In this work, we introduce a polarizable molecular orbital model Hamiltonian for water and for oxygen- and hydrogen-containing compounds, whereas the electrostatic potential responsible for intermolecular interactions in the liquid and in solution is modeled by a three-point charge representation that realistically reproduces the total molecular dipole moment and the local hybridization contributions. The present QMFF for water, which is called the XP3P (explicit polarization with three-point-charge potential) model, is suitable for modeling both gas-phase clusters and liquid water. The paper demonstrates the performance of the XP3P model for water and proton clusters and the properties of the pure liquid from about 900 × 10(6) self-consistent-field calculations on a periodic system consisting of 267 water molecules. The unusual dipole derivative behavior of water, which is incorrectly modeled in molecular mechanics, is naturally reproduced as a result of an electronic structural treatment of chemical bonding by XP3P. We anticipate that the XP3P model will be useful for studying proton transport in solution and solid phases as well as across biological ion channels through membranes.
Collapse
Affiliation(s)
- Jaebeom Han
- Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant Street, SE, Minneapolis, Minnesota 55455-0431, USA
| | | | | | | | | |
Collapse
|
19
|
Kandathil SM, Fletcher TL, Yuan Y, Knowles J, Popelier PLA. Accuracy and tractability of a kriging model of intramolecular polarizable multipolar electrostatics and its application to histidine. J Comput Chem 2013; 34:1850-61. [PMID: 23720381 DOI: 10.1002/jcc.23333] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 04/23/2013] [Accepted: 04/24/2013] [Indexed: 11/05/2022]
Abstract
We propose a generic method to model polarization in the context of high-rank multipolar electrostatics. This method involves the machine learning technique kriging, here used to capture the response of an atomic multipole moment of a given atom to a change in the positions of the atoms surrounding this atom. The atoms are malleable boxes with sharp boundaries, they do not overlap and exhaust space. The method is applied to histidine where it is able to predict atomic multipole moments (up to hexadecapole) for unseen configurations, after training on 600 geometries distorted using normal modes of each of its 24 local energy minima at B3LYP/apc-1 level. The quality of the predictions is assessed by calculating the Coulomb energy between an atom for which the moments have been predicted and the surrounding atoms (having exact moments). Only interactions between atoms separated by three or more bonds ("1, 4 and higher" interactions) are included in this energy error. This energy is compared with that of a central atom with exact multipole moments interacting with the same environment. The resulting energy discrepancies are summed for 328 atom-atom interactions, for each of the 29 atoms of histidine being a central atom in turn. For 80% of the 539 test configurations (outside the training set), this summed energy deviates by less than 1 kcal mol(-1).
Collapse
Affiliation(s)
- Shaun M Kandathil
- Manchester Institute of Biotechnology, 131 Princess Street, Manchester, M1 7DN, United Kingdom
| | | | | | | | | |
Collapse
|
20
|
Zeng J, Duan L, Zhang JZ, Mei Y. A numerically stable restrained electrostatic potential charge fitting method. J Comput Chem 2012; 34:847-53. [DOI: 10.1002/jcc.23208] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 11/08/2012] [Accepted: 11/28/2012] [Indexed: 12/11/2022]
|
21
|
Zhang P, Truhlar DG, Gao J. Fragment-based quantum mechanical methods for periodic systems with Ewald summation and mean image charge convention for long-range electrostatic interactions. Phys Chem Chem Phys 2012; 14:7821-9. [PMID: 22552612 PMCID: PMC3517951 DOI: 10.1039/c2cp23758j] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe an Ewald-summation method to incorporate long-range electrostatic interactions into fragment-based electronic structure methods for periodic systems. The present method is an extension of the particle-mesh Ewald technique for combined quantum mechanical and molecular mechanical (QM/MM) calculations, and it has been implemented into the explicit polarization (X-Pol) potential to illustrate the computational details. As in the QM/MM-Ewald method, the X-Pol-Ewald approach is a linear-scaling electrostatic method, in which the short-range electrostatic interactions are determined explicitly in real space and the long-range Ewald pair potential is incorporated into the Fock matrix as a correction. To avoid the time-consuming Fock matrix update during the self-consistent field procedure, a mean image charge (MIC) approximation is introduced, in which the running average with a user-chosen correlation time is used to represent the long-range electrostatic correction as an average effect. Test simulations on liquid water show that the present X-Pol-Ewald method takes about 25% more CPU time than the usual X-Pol method using spherical cutoff, whereas the use of the MIC approximation reduces the extra costs for long-range electrostatic interactions by 15%. The present X-Pol-Ewald method provides a general procedure for incorporating long-range electrostatic effects into fragment-based electronic structure methods for treating biomolecular and condensed-phase systems under periodic boundary conditions.
Collapse
Affiliation(s)
- Peng Zhang
- Department of Chemistry, Digital Technology Center and Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455
| | - Donald G. Truhlar
- Department of Chemistry, Digital Technology Center and Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455
| | - Jiali Gao
- Department of Chemistry, Digital Technology Center and Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455
| |
Collapse
|
22
|
Wang Y, Sosa CP, Cembran A, Truhlar DG, Gao J. Multilevel X-Pol: a fragment-based method with mixed quantum mechanical representations of different fragments. J Phys Chem B 2012; 116:6781-8. [PMID: 22428657 DOI: 10.1021/jp212399g] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The explicit polarization (X-Pol) method is a fragment-based quantum mechanical model, in which a macromolecular system or other large or complex system in solution is partitioned into monomeric fragments. The present study extends the original X-Pol method, where all fragments are treated using the same electronic structure theory, to multilevel representations, called multilevel X-Pol, in which different electronic structure methods are used to describe different fragments. The multilevel X-Pol method has been implemented into a locally modified version of Gaussian 09. A key ingredient that is used to couple interfragment electrostatic interactions at different levels of theory is the use of the response density for the post-self-consistent-field energy. (The response density is also called the generalized density.) The method is useful for treating fragments in a small region of the system such as a solute molecule or the substrate and amino acids in the active site of an enzyme with a high-level theory, and the fragments in the rest of the system by a lower-level and computationally more efficient method. Multilevel X-Pol is illustrated here by applications to hydrogen bonding complexes in which one fragment is treated with the hybrid M06 density functional, Møller-Plesset perturbation theory, or coupled cluster theory, and the other fragments are treated by Hartree-Fock theory or the B3LYP or M06 hybrid density functionals.
Collapse
Affiliation(s)
- Yingjie Wang
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | | | | | | | | |
Collapse
|
23
|
Isegawa M, Gao J, Truhlar DG. Incorporation of charge transfer into the explicit polarization fragment method by grand canonical density functional theory. J Chem Phys 2011; 135:084107. [PMID: 21895159 DOI: 10.1063/1.3624890] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Molecular fragmentation algorithms provide a powerful approach to extending electronic structure methods to very large systems. Here we present a method for including charge transfer between molecular fragments in the explicit polarization (X-Pol) fragment method for calculating potential energy surfaces. In the conventional X-Pol method, the total charge of each fragment is preserved, and charge transfer between fragments is not allowed. The description of charge transfer is made possible by treating each fragment as an open system with respect to the number of electrons. To achieve this, we applied Mermin's finite temperature method to the X-Pol wave function. In the application of this method to X-Pol, the fragments are open systems that partially equilibrate their number of electrons through a quasithermodynamics electron reservoir. The number of electrons in a given fragment can take a fractional value, and the electrons of each fragment obey the Fermi-Dirac distribution. The equilibrium state for the electrons is determined by electronegativity equalization with conservation of the total number of electrons. The amount of charge transfer is controlled by re-interpreting the temperature parameter in the Fermi-Dirac distribution function as a coupling strength parameter. We determined this coupling parameter so as to reproduce the charge transfer energy obtained by block localized energy decomposition analysis. We apply the new method to ten systems, and we show that it can yield reasonable approximations to potential energy profiles, to charge transfer stabilization energies, and to the direction and amount of charge transferred.
Collapse
Affiliation(s)
- Miho Isegawa
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | | | | |
Collapse
|