An efficient, monomer-based electronic structure method is introduced for computing non-covalent interactions in molecular and ionic clusters. It builds upon our ''explicit polarization'' (XPol) with pairwise-additive symmetry-adapted perturbation theory (SAPT) using the Kohn-Sham (KS) version of SAPT, but replaces the problematic and expensive sum-over-states dispersion terms with empirical potentials. This modification reduces the scaling from O(N5) to O(N3) and also facilitates the use of Kohn-Sham density functional theory (KS-DFT) as a low-cost means to capture intramolecular electron correlation. The new method [XSAPT(KS)+D2] gives accurate binding energies for dimer benchmark databases and describes the whole potential energy curves accurately for a variety of challenging systems yet is efficient enough to be applied to systems containing numerous monomer units. An accurate interaction-energy decomposition scheme for this method is also introduced and extends traditional SAPT energy decomposition analysis to many-body systems. These characteristics make XSAPT(KS)+D2 as a promising method for use in fragment-based drug design.

Accurate intermolecular interaction energy components for many-body systems

246th National Meeting (2013)

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