Density functional Theory Based Generalized Effective Fragment Potential Method (Postprint)
Interim rept. 28 Mar 2013-3 Jun 2014
GENERAL DYNAMICS INFORMATION TECHNOLOGY INC DAYTON OH
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We present a generalized Kohn-Sham KS density functional theory DFT based effective fragment potential EFP2-DFT method for the treatment of solvent effects. Similar to the original Hartree-Fock HF based potential with fitted parameters for water EFP1 and the generalized HF based potential EFP2-HF, EFP2-DFT includes electrostatic, exchange-repulsion, polarization, and dispersion potentials, which are generated for a chosen DFT functional for a given isolated molecule. The method does not have fitted parameters, except for implicit parameters within a chosen functional and the dispersion correction to the potential. The electrostatic potential is modeled with a multipolar expansion at each atomic center and bond midpoint using Stones distributed multipolar analysis. The exchange-repulsion potential between two fragments is composed of the overlap and kinetic energy integrals and the nondiagonal KS matrices in the localized molecular orbital basis. The polarization potential is derived from the static molecular polarizability. The dispersion potential includes the intermolecular D3 dispersion correction of Grimme et al. J. Chem. Phys. 132, 154104 2010. The potential generated from the CAMB3LYP functional has mean unsigned errors MUEs with respect to results from coupled cluster singles, doubles, and perturbative triples with a complete basis set limit CCSDTCBS extrapolation, of 1.7, 2.2, 2.0, and 0.5 kcalmol, for the S22, water-benzene clusters, water clusters, and n-alkane dimers benchmark sets, respectively. The corresponding EFP2-HF errors for the respective benchmarks are 2.41, 3.1, 1.8, and 2.5 kcalmol. Thus, the new EFP2-DFT-D3 method with the CAMB3LYP functional provides comparable or improved results at lower computational cost and, therefore, extends the range of applicability of EFP2 to larger system sizes.
- Physical Chemistry
- Operations Research
- Atomic and Molecular Physics and Spectroscopy