Application of Explicitly Localized Molecular Orbitals to Electronic Structure Calculations

Abstract

We have recently generalized the method for localizing orbitals on a set of predefined molecular fragments [Phys. Chem. Chem. Phys. 2012, 14, 546]. The regional localized molecular orbitals (RLMO) are well suited for exploiting the locality of electronic correlation at post-Hartree-Fock level of theory. In this paper, the adequacy of RLMO representation is tested in the second-order local Møller-Plesset (LMP2) perturbation theory. Two model systems, namely, n-pentadecane and trans-retinal, are considered. Adequacy of RLMO/LMP2 method is discussed in conjunction with 'exact' MP2 and Pipek-Mezey LMP2 calculations. It is demonstrated that RLMO/MP2 method reduces correlation space and reproduces more than 99% of the correlation energy.