Electron correlation by polarization of interacting densities

TL;DR

This paper introduces a method to incorporate dynamical electron correlation effects into electronic structure calculations by polarizing interacting densities, reducing Coulomb interaction magnitudes without expanding the basis set.

Contribution

The novel approach allows for accounting of dynamical correlation effects through polarization of densities, avoiding the need for higher spherical harmonic functions in the basis.

Findings

Effective in atoms, ions, and molecules with various bonding and spin states.

Reduces Coulomb interaction magnitude via density polarization.

Applicable in single-determinant and configuration interaction calculations.

Abstract

Coulomb interactions that occur in electronic structure calculations are correlated by allowing basis function components of the interacting densities to polarize, thereby reducing the magnitude of the interaction. Exchange integrals of molecular orbitals are not correlated. The modified Coulomb interactions are used in single-determinant or configuration interaction calculations. The objective is to account for dynamical correlation effects without explicitly introducing higher spherical harmonic functions into the molecular orbital basis. Molecular orbital densities are decomposed into a distribution of spherical components that conserve the charge and each of the interacting components is considered as a two-electron wavefunction embedded in the system acted on by an average field Hamiltonian plus . A method of avoiding redundancy is described. Applications to atoms, negative ions and molecules representing different types of bonding and spin states are discussed.