Premium
Optimization of a molecular mechanics force field for type‐II polyoxometalates focussing on electrostatic interactions: A case study
Author(s) -
Courcot Blandine,
Bridgeman Adam J.
Publication year - 2011
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.21752
Subject(s) - van der waals force , force field (fiction) , scaling , electrostatics , partial charge , chemistry , field (mathematics) , molecular mechanics , chemical physics , type (biology) , molecule , computational chemistry , molecular dynamics , statistical physics , physics , quantum mechanics , mathematics , geometry , organic chemistry , pure mathematics , ecology , biology
Abstract In this study, we have focussed on type‐II polyanions such as [M 7 O 24 ] 6− , and we have developed and validated optimized force fields that include electrostatic and van der Waals interactions. These contributions to the total steric energy are described by the nonbonded term, which encompasses all interactions between atoms that are not transmitted through the bonds. A first validation of a stochastic technique based on genetic algorithms was previously made for the optimization of force fields dedicated to type‐I polyoxometalates. To describe the new nonbonded term added in the functional, a fixed‐charged model was chosen. Therefore, one of the main issues was to analyze that which partial atomic charges could be reliably used to describe these interactions in such inorganic compounds. Based on several computational strategies, molecular mechanics (MM) force field parameters were optimized using different types of atomic charges. Moreover, the influence of the electrostatic and van der Waals buffering constants and 1,4‐interactions scaling factors used in the force field were also tested, either being optimized as well or fixed with respect to the values of CHARMM force field. Results show that some atomic charges are not well adapted to CHARMM parameters and lead to unrealistic MM‐optimized structures or a MM divergence. As a result, a new scaling factor has been optimized for Quantum Theory of Atoms in Molecules charges and charges derived from the electrostatic potential such as ChelpG. The force fields optimized can be mixed with the CHARMM force field, without changing it, to study for the first time hepta‐anions interacting with organic molecules. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011