Corrected small basis set Hartree-Fock method for large systems

A quantum chemical method based on a Hartree‐Fock calculation with a small Gaussian AO basis set is presented. Its main area of application is the computation of structures, vibrational frequencies, and noncovalent interaction energies in huge molecular systems. The method is suggested as a partial replacement of semiempirical approaches or density functional theory (DFT) in particular when self‐interaction errors are acute. In order to get accurate results three physically plausible atom pair‐wise correction terms are applied for London dispersion interactions (D3 scheme), basis set superposition error (gCP scheme), and short‐ranged basis set incompleteness effects. In total nine global empirical parameters are used. This so‐called Hartee‐Fock‐3c (HF‐3c) method is tested for geometries of small organic molecules, interaction energies and geometries of noncovalently bound complexes, for supramolecular systems, and protein structures. In the majority of realistic test cases good results approaching large basis set DFT quality are obtained at a tiny fraction of computational cost. © 2013 Wiley Periodicals, Inc. A newly developed HF‐3c quantum chemical protocol combines a Hartree–Fock/small basis set calculation with three physically plausible atom pair‐wise correction terms. It yields good results for noncovalent interactions, geometries of organic molecules, supramolecular complexes, and small proteins. For most test cases, its accuracy approaches the density functional theory (DFT)‐dispersion correction scheme (D3), large basis set quality, which is obtained at a tiny fraction the of computational cost and can be applied to large molecular systems as an alternative to semiempirical methods.