1
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Snyder R, Kim B, Pan X, Shao Y, Pu J. Bridging semiempirical and ab initio QM/MM potentials by Gaussian process regression and its sparse variants for free energy simulation. J Chem Phys 2023; 159:054107. [PMID: 37530109 PMCID: PMC10400118 DOI: 10.1063/5.0156327] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 07/10/2023] [Indexed: 08/03/2023] Open
Abstract
Free energy simulations that employ combined quantum mechanical and molecular mechanical (QM/MM) potentials at ab initio QM (AI) levels are computationally highly demanding. Here, we present a machine-learning-facilitated approach for obtaining AI/MM-quality free energy profiles at the cost of efficient semiempirical QM/MM (SE/MM) methods. Specifically, we use Gaussian process regression (GPR) to learn the potential energy corrections needed for an SE/MM level to match an AI/MM target along the minimum free energy path (MFEP). Force modification using gradients of the GPR potential allows us to improve configurational sampling and update the MFEP. To adaptively train our model, we further employ the sparse variational GP (SVGP) and streaming sparse GPR (SSGPR) methods, which efficiently incorporate previous sample information without significantly increasing the training data size. We applied the QM-(SS)GPR/MM method to the solution-phase SN2 Menshutkin reaction, NH3+CH3Cl→CH3NH3++Cl-, using AM1/MM and B3LYP/6-31+G(d,p)/MM as the base and target levels, respectively. For 4000 configurations sampled along the MFEP, the iteratively optimized AM1-SSGPR-4/MM model reduces the energy error in AM1/MM from 18.2 to 4.4 kcal/mol. Although not explicitly fitting forces, our method also reduces the key internal force errors from 25.5 to 11.1 kcal/mol/Å and from 30.2 to 10.3 kcal/mol/Å for the N-C and C-Cl bonds, respectively. Compared to the uncorrected simulations, the AM1-SSGPR-4/MM method lowers the predicted free energy barrier from 28.7 to 11.7 kcal/mol and decreases the reaction free energy from -12.4 to -41.9 kcal/mol, bringing these results into closer agreement with their AI/MM and experimental benchmarks.
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Affiliation(s)
- Ryan Snyder
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, 402 N Blackford St., Indianapolis, Indiana 46202, USA
| | - Bryant Kim
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, 402 N Blackford St., Indianapolis, Indiana 46202, USA
| | - Xiaoliang Pan
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Pkwy, Norman, Oklahoma 73019, USA
| | - Yihan Shao
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Pkwy, Norman, Oklahoma 73019, USA
| | - Jingzhi Pu
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, 402 N Blackford St., Indianapolis, Indiana 46202, USA
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2
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Snyder R, Kim B, Pan X, Shao Y, Pu J. Facilitating ab initio QM/MM free energy simulations by Gaussian process regression with derivative observations. Phys Chem Chem Phys 2022; 24:25134-25143. [PMID: 36222412 PMCID: PMC11095978 DOI: 10.1039/d2cp02820d] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
In combined quantum mechanical and molecular mechanical (QM/MM) free energy simulations, how to synthesize the accuracy of ab initio (AI) methods with the speed of semiempirical (SE) methods for a cost-effective QM treatment remains a long-standing challenge. In this work, we present a machine-learning-facilitated method for obtaining AI/MM-quality free energy profiles through efficient SE/MM simulations. In particular, we use Gaussian process regression (GPR) to learn the energy and force corrections needed for SE/MM to match with AI/MM results during molecular dynamics simulations. Force matching is enabled in our model by including energy derivatives into the observational targets through the extended-kernel formalism. We demonstrate the effectiveness of this method on the solution-phase SN2 Menshutkin reaction using AM1/MM and B3LYP/6-31+G(d,p)/MM as the base and target levels, respectively. Trained on only 80 configurations sampled along the minimum free energy path (MFEP), the resulting GPR model reduces the average energy error in AM1/MM from 18.2 to 5.8 kcal mol-1 for the 4000-sample testing set with the average force error on the QM atoms decreased from 14.6 to 3.7 kcal mol-1 Å-1. Free energy sampling with the GPR corrections applied (AM1-GPR/MM) produces a free energy barrier of 14.4 kcal mol-1 and a reaction free energy of -34.1 kcal mol-1, in closer agreement with the AI/MM benchmarks and experimental results.
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Affiliation(s)
- Ryan Snyder
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, 402 N. Blackford St., Indianapolis, IN 46202, USA.
| | - Bryant Kim
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, 402 N. Blackford St., Indianapolis, IN 46202, USA.
| | - Xiaoliang Pan
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Pkwy, Norman, OK 73019, USA.
| | - Yihan Shao
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Pkwy, Norman, OK 73019, USA.
| | - Jingzhi Pu
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, 402 N. Blackford St., Indianapolis, IN 46202, USA.
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3
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Chen Z, Wu W. Ab initio valence bond theory: A brief history, recent developments, and near future. J Chem Phys 2020; 153:090902. [PMID: 32891101 DOI: 10.1063/5.0019480] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
This Perspective presents a survey of several issues in ab initio valence bond (VB) theory with a primary focus on recent advances made by the Xiamen VB group, including a brief review of the earlier history of the ab initio VB methods, in-depth discussion of algorithms for nonorthogonal orbital optimization in the VB self-consistent field method and VB methods incorporating dynamic electron correlation, along with a concise overview of VB methods for complex systems and VB models for chemical bonding and reactivity, and an outlook of opportunities and challenges for the near future of the VB theory.
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Affiliation(s)
- Zhenhua Chen
- Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, The State Key Laboratory of Physical Chemistry of Solid Surfaces, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Wei Wu
- Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, The State Key Laboratory of Physical Chemistry of Solid Surfaces, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
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4
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Saez DA, Vogt-Geisse S, Inostroza-Rivera R, Kubař T, Elstner M, Toro-Labbé A, Vöhringer-Martinez E. The effect of the environment on the methyl transfer reaction mechanism between trimethylsulfonium and phenolate. Phys Chem Chem Phys 2016; 18:24033-42. [DOI: 10.1039/c6cp02821g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The methyl transfer reaction mechanism in different molecular environments were studied by electronic structure methods and QM/MM molecular dynamics simulations.
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Affiliation(s)
- David Adrian Saez
- Departamento de Físico-Química
- Facultad de Ciencias Químicas
- Universidad de Concepción
- Millenium Nucleus Chemical Processes and Catalysis (CPC)
- Chile
| | - Stefan Vogt-Geisse
- Departamento de Físico-Química
- Facultad de Ciencias Químicas
- Universidad de Concepción
- Millenium Nucleus Chemical Processes and Catalysis (CPC)
- Chile
| | | | - Tomáš Kubař
- Center for Functional Nanomaterials
- Karlsruhe Institute of Technology
- Germany
- Institute for Physical Chemistry
- Karlsruhe Institute of Technology
| | - Marcus Elstner
- Institute for Physical Chemistry
- Karlsruhe Institute of Technology
- 76131 Karlsruhe
- Germany
| | - Alejandro Toro-Labbé
- QTC
- Facultad de Química
- Pontificia Universidad Católica de Chile
- Millenium Nucleus Chemical Processes and Catalysis (CPC)
- Chile
| | - Esteban Vöhringer-Martinez
- Departamento de Físico-Química
- Facultad de Ciencias Químicas
- Universidad de Concepción
- Millenium Nucleus Chemical Processes and Catalysis (CPC)
- Chile
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5
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Kido K, Kasahara K, Yokogawa D, Sato H. A hybrid framework of first principles molecular orbital calculations and a three-dimensional integral equation theory for molecular liquids: multi-center molecular Ornstein-Zernike self-consistent field approach. J Chem Phys 2015; 143:014103. [PMID: 26156461 DOI: 10.1063/1.4923007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In this study, we reported the development of a new quantum mechanics/molecular mechanics (QM/MM)-type framework to describe chemical processes in solution by combining standard molecular-orbital calculations with a three-dimensional formalism of integral equation theory for molecular liquids (multi-center molecular Ornstein-Zernike (MC-MOZ) method). The theoretical procedure is very similar to the 3D-reference interaction site model self-consistent field (RISM-SCF) approach. Since the MC-MOZ method is highly parallelized for computation, the present approach has the potential to be one of the most efficient procedures to treat chemical processes in solution. Benchmark tests to check the validity of this approach were performed for two solute (solute water and formaldehyde) systems and a simple SN2 reaction (Cl(-) + CH3Cl → ClCH3 + Cl(-)) in aqueous solution. The results for solute molecular properties and solvation structures obtained by the present approach were in reasonable agreement with those obtained by other hybrid frameworks and experiments. In particular, the results of the proposed approach are in excellent agreements with those of 3D-RISM-SCF.
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Affiliation(s)
- Kentaro Kido
- Nuclear Safety Research Center, Japan Atomic Energy Agency, 2-4 Shirane, Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Kento Kasahara
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Daisuke Yokogawa
- Department of Chemistry, Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan
| | - Hirofumi Sato
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
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Shurki A, Derat E, Barrozo A, Kamerlin SCL. How valence bond theory can help you understand your (bio)chemical reaction. Chem Soc Rev 2015; 44:1037-52. [DOI: 10.1039/c4cs00241e] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This Tutorial Review describes modern VB theory, using a didactic example of an SN2 reaction to illustrate its immediate applications.
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Affiliation(s)
- Avital Shurki
- Institute for Drug Research
- School of Pharmacy
- The Hebrew University of Jerusalem
- Jerusalem
- Israel
| | - Etienne Derat
- Institut Parisien de Chimie Moléculaire
- UMR 8232
- Paris
- France
| | - Alexandre Barrozo
- Science for Life Laboratory
- Department of Cell and Molecular Biology
- Uppsala University
- Uppsala
- Sweden
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7
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VBEFP/PCM: a QM/MM/PCM approach for valence-bond method and its application for the vertical excitations of formaldehyde and acetone in aqueous solution. Sci China Chem 2014. [DOI: 10.1007/s11426-014-5192-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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8
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Shurki A, Sharir-Ivry A. Valence Bond-Based Hybrid Quantum Mechanics Molecular Mechanics Approaches and Proper Inclusion of the Effect of the Surroundings. Isr J Chem 2014. [DOI: 10.1002/ijch.201400038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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9
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Acevedo O, Jorgensen WL. Quantum and Molecular Mechanical (QM/MM) Monte Carlo Techniques for Modeling Condensed-Phase Reactions. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2014; 4:422-435. [PMID: 25431625 DOI: 10.1002/wcms.1180] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A recent review (Acc. Chem. Res. 2010, 43:142-151) examined our use and development of a combined quantum and molecular mechanical (QM/MM) technique for modelling organic and enzymatic reactions. Advances included the PDDG/PM3 semiempirical QM (SQM) method, computation of multi-dimensional potentials of mean force (PMF), incorporation of on-the-fly QM in Monte Carlo simulations, and a polynomial quadrature method for rapidly treating proton-transfer reactions. The current article serves as a follow up on our progress. Highlights include new reactions, alternative SQM methods, a polarizable OPLS force field, and novel solvent environments, e.g., "on water" and room temperature ionic liquids. The methodology is strikingly accurate across a wide range of condensed-phase and antibody-catalyzed reactions including substitution, decarboxylation, elimination, isomerization, and pericyclic classes. Comparisons are made to systems treated with continuum-based solvents and ab initio or density functional theory (DFT) methods. Overall, the QM/MM methodology provides detailed characterization of reaction paths, proper configurational sampling, several advantages over implicit solvent models, and a reasonable computational cost.
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Affiliation(s)
- Orlando Acevedo
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849
| | - Wiliiam L Jorgensen
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520-8107
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10
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Klippenstein SJ, Pande VS, Truhlar DG. Chemical Kinetics and Mechanisms of Complex Systems: A Perspective on Recent Theoretical Advances. J Am Chem Soc 2014; 136:528-46. [DOI: 10.1021/ja408723a] [Citation(s) in RCA: 187] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Stephen J. Klippenstein
- Chemical
Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Vijay S. Pande
- Department
of Chemistry and Structural Biology, Stanford University, Stanford, California 94305, United States
| | - Donald G. Truhlar
- Department
of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
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11
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Computer-aided molecular design of solvents for accelerated reaction kinetics. Nat Chem 2013; 5:952-7. [DOI: 10.1038/nchem.1755] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 08/12/2013] [Indexed: 11/08/2022]
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12
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Li Y, Hartke B. Assessing Solvation Effects on Chemical Reactions with Globally Optimized Solvent Clusters. Chemphyschem 2013; 14:2678-86. [DOI: 10.1002/cphc.201300323] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Indexed: 11/09/2022]
Affiliation(s)
- Yan Li
- Institut für Physikalische Chemie, Christian‐Albrechts‐Universität, Olshausenstr. 40, 24098 Kiel (Germany)
| | - Bernd Hartke
- Institut für Physikalische Chemie, Christian‐Albrechts‐Universität, Olshausenstr. 40, 24098 Kiel (Germany)
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13
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Chen Z, Chen X, Wu W. Nonorthogonal orbital basedN-body reduced density matrices and their applications to valence bond theory. I. Hamiltonian matrix elements between internally contracted excited valence bond wave functions. J Chem Phys 2013; 138:164119. [DOI: 10.1063/1.4801631] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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14
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Chen Z, Chen X, Wu W. Nonorthogonal orbital based N-body reduced density matrices and their applications to valence bond theory. II. An efficient algorithm for matrix elements and analytical energy gradients in VBSCF method. J Chem Phys 2013; 138:164120. [DOI: 10.1063/1.4801632] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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15
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Nakano H, Yamamoto T. Accurate and Efficient Treatment of Continuous Solute Charge Density in the Mean-Field QM/MM Free Energy Calculation. J Chem Theory Comput 2012; 9:188-203. [DOI: 10.1021/ct300831t] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Hiroshi Nakano
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Takeshi Yamamoto
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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16
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Song J, Chen Z, Shaik S, Wu W. An efficient algorithm for complete active space valence bond self-consistent field calculation. J Comput Chem 2012; 34:38-48. [DOI: 10.1002/jcc.23103] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Revised: 08/01/2012] [Accepted: 08/07/2012] [Indexed: 01/14/2023]
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17
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Su P, Wu W. Ab initio
nonorthogonal valence bond methods. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2012. [DOI: 10.1002/wcms.1105] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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18
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Ying F, Chang X, Su P, Wu W. VBEFP: A Valence Bond Approach That Incorporates Effective Fragment Potential Method. J Phys Chem A 2012; 116:1846-53. [DOI: 10.1021/jp211314j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Fuming Ying
- The State Key Laboratory of Physical
Chemistry of Solid
Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational
Chemistry and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Xin Chang
- The State Key Laboratory of Physical
Chemistry of Solid
Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational
Chemistry and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Peifeng Su
- The State Key Laboratory of Physical
Chemistry of Solid
Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational
Chemistry and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Wei Wu
- The State Key Laboratory of Physical
Chemistry of Solid
Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational
Chemistry and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
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19
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Wu W, Su P, Shaik S, Hiberty PC. Classical Valence Bond Approach by Modern Methods. Chem Rev 2011; 111:7557-93. [DOI: 10.1021/cr100228r] [Citation(s) in RCA: 200] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Wei Wu
- The State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Peifeng Su
- The State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Sason Shaik
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University, Jerusalem 91904, Israel
| | - Philippe C. Hiberty
- Laboratoire de Chimie Physique, Groupe de Chimie Théorique, CNRS UMR 8000, Université de Paris-Sud, 91405 Orsay Cédex, France
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20
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Vilseck JZ, Sambasivarao SV, Acevedo O. Optimal scaling factors for CM1 and CM3 atomic charges in RM1‐based aqueous simulations. J Comput Chem 2011; 32:2836-42. [DOI: 10.1002/jcc.21863] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 05/04/2011] [Accepted: 05/15/2011] [Indexed: 11/10/2022]
Affiliation(s)
- Jonah Z. Vilseck
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849
| | | | - Orlando Acevedo
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849
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21
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Shaik S, Hiberty PC. A primer on qualitative valence bond theory – a theory coming of age. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2011. [DOI: 10.1002/wcms.7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Sason Shaik
- Institute of Chemistry and the Lise Meitner‐Minerva Center for Computational Quantum Chemisty, The Edmond J. Safra Campus‐Givat Ram, The Hebrew University, Jerusalem, Israel
| | - Philippe C. Hiberty
- Laboratoire de Chimie Physique, CNRS UMR 8000, Bat 349, Université de Paris‐Sud, 19405 Orsay, France
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22
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Acevedo O, Jorgensen WL. Exploring solvent effects upon the Menshutkin reaction using a polarizable force field. J Phys Chem B 2010; 114:8425-30. [PMID: 20527873 PMCID: PMC2903038 DOI: 10.1021/jp100765v] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The energetics of the Menshutkin reaction between triethylamine and ethyl iodide have been computed using B3LYP and MP2 with the LANL2DZ, LANL2DZd, SVP, MIDI!, 6-311G(d,p), and aug-cc-PVTZ basis sets. Small- and large-core energy-consistent relativistic pseudopotentials were employed. Solvent effect corrections were computed from QM/MM Monte Carlo simulations utilizing free-energy perturbation theory, PDDG/PM3, and both a nonpolarizable OPLS and polarizable OPLS-AAP force field. The B3LYP/MIDI! theory level provided the best DeltaG(++) values with a mean absolute error (MAE) of 4.9 kcal/mol from experiment in cyclohexane, CCl(4), THF, DMSO, acetonitrile, water, and methanol. However, the relative rates in cyclohexane, and to a certain extent CCl(4), were determined to be greatly underestimated when using the nonpolarizable OPLS force field. An overall reduction in the MAE to 3.1 kcal/mol using B3LYP/MIDI!/OPLS-AAP demonstrated the need for a fully polarizable force field when computing solvent effects for highly dipolar transition structures in low-dielectric media. The MAEs obtained with PDDG/PM3/OPLS and OPLS-AAP of 5.3 and 3.8 kcal/mol, respectively, provided comparable results to B3LYP at a fraction of the computational resources. The large rate accelerations observed in the reaction were correlated to an increased stabilization of the emerging charge separation at the transition state via favorable solute-solvent interactions.
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Affiliation(s)
- Orlando Acevedo
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA.
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Valero R, Song L, Gao J, Truhlar DG. Perspective on Diabatic Models of Chemical Reactivity as Illustrated by the Gas-Phase S(N)2 Reaction of Acetate Ion with 1,2-Dichloroethane. J Chem Theory Comput 2009; 5:1-22. [PMID: 20047005 PMCID: PMC2658610 DOI: 10.1021/ct800318h] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Diabatic models are widely employed for studying chemical reactivity in condensed phases and enzymes, but there has been little discussion of the pros and cons of various diabatic representations for this purpose. Here we discuss and contrast six different schemes for computing diabatic potentials for a charge rearrangement reaction. They include (i) the variational diabatic configurations (VDC) constructed by variationally optimizing individual valence bond structures and (ii) the consistent diabatic configurations (CDC) obtained by variationally optimizing the ground-state adiabatic energy, both in the nonorthogonal molecular orbital valence bond (MOVB) method, along with the orthogonalized (iii) VDC-MOVB and (iv) CDC-MOVB models. In addition, we consider (v) the fourfold way (based on diabatic molecular orbitals and configuration uniformity), and (vi) empirical valence bond (EVB) theory. To make the considerations concrete, we calculate diabatic electronic states and diabatic potential energies along the reaction path that connects the reactant and the product ion-molecule complexes of the gas-phase bimolecular nucleophilic substitution (S(N)2) reaction of 1,2-dichloethane (DCE) with acetate ion, which is a model reaction corresponding to the reaction catalyzed by haloalkane dehalogenase. We utilize ab initio block-localized molecular orbital theory to construct the MOVB diabatic states and ab initio multi-configuration quasidegenerate perturbation theory to construct the fourfold-way diabatic states; the latter are calculated at reaction path geometries obtained with the M06-2X density functional. The EVB diabatic states are computed with parameters taken from the literature. The MOVB and fourfold-way adiabatic and diabatic potential energy profiles along the reaction path are in qualitative but not quantitative agreement with each other. In order to validate that these wave-function-based diabatic states are qualitatively correct, we show that the reaction energy and barrier for the adiabatic ground state, obtained with these methods, agree reasonably well with the results of high-level calculations using the composite G3SX and G3SX(MP3) methods and the BMC-CCSD multi-coefficient correlation method. However, a comparison of the EVB gas-phase adiabatic ground-state reaction path with those obtained from MOVB and with the fourfold way reveals that the EVB reaction path geometries show a systematic shift towards the products region, and that the EVB lowest-energy path has a much lower barrier. The free energies of solvation and activation energy in water reported from dynamical calculations based on EVB also imply a low activation barrier in the gas phase. In addition, calculations of the free energy of solvation using the recently proposed SM8 continuum solvation model with CM4M partial atomic charges lead to an activation barrier in reasonable agreement with experiment only when the geometries and the gas-phase barrier are those obtained from electronic structure calculations, i.e., methods i-v. These comparisons show the danger of basing the diabatic states on molecular mechanics without the explicit calculation of electronic wave functions. Furthermore, comparison of schemes i-v with one another shows that significantly different quantitative results can be obtained by using different methods for extracting diabatic states from wave function calculations, and it is important for each user to justify the choice of diabatization method in the context of its intended use.
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Affiliation(s)
- Rosendo Valero
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455-0431
| | - Lingchun Song
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455-0431
| | - Jiali Gao
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455-0431
| | - Donald G. Truhlar
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455-0431
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