Towards a force field based on density fitting

Jean‐Philip Piquemal

doi:10.1063/1.2173256

2006-03-08

195

DOI：10.1063/1.2173256

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摘要

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Total intermolecular interaction energies are determined with a first version of the Gaussian electrostatic model (GEM-0), a force field based on a density fitting approach using s-type Gaussian functions. The total interaction energy is computed in the spirit of the sum of interacting fragment ab initio (SIBFA) force field by separately evaluating each one of its components: electrostatic (Coulomb), exchange repulsion, polarization, and charge transfer intermolecular interaction energies, in order to reproduce reference constrained space orbital variation (CSOV) energy decomposition calculations at the B3LYP/aug-cc-pVTZ level. The use of an auxiliary basis set restricted to spherical Gaussian functions facilitates the rotation of the fitted densities of rigid fragments and enables a fast and accurate density fitting evaluation of Coulomb and exchange-repulsion energy, the latter using the overlap model introduced by Wheatley and Price [Mol. Phys. 69, 50718 (1990)]. The SIBFA energy scheme for polarization and charge transfer has been implemented using the electric fields and electrostatic potentials generated by the fitted densities. GEM-0 has been tested on ten stationary points of the water dimer potential energy surface and on three water clusters (n=16,20,64). The results show very good agreement with density functional theory calculations, reproducing the individual CSOV energy contributions for a given interaction as well as the B3LYP total interaction energies with errors below k(B)T at room temperature. Preliminary results for Coulomb and exchange-repulsion energies of metal cation complexes and coupled cluster singles doubles electron densities are discussed. (c) 2006 American Institute of Physics.

Keyword:

INTERMOLECULAR INTERACTION ENERGY

POLARIZABLE MOLECULAR-MECHANICS

CHARGE-TRANSFER CONTRIBUTION

BASIS-SETS

ADDITIVE PROCEDURE

ELECTRON-DENSITY

WATER DIMER

POTENTIALS

COMPUTATIONS

ATOMS