Numerical multiconfigurational Hartree–Fock calculations of spin and charge densities using the Hiller–Sucher–Feinberg operator identity

Abstract

The Hiller–Sucher–Feinberg operator has been implemented into the atomic finite-element multiconfiguration spin-restricted Hartree–Fock program lucas. The spin-dependent and spin-independent Hiller–Sucher–Feinberg operators have been tested on Li(2Se), Be(3Po), B(2Po), C(3Pe), N(4So), O(3Pe), and F(2Po) using numerical and Gaussian sp basis sets. In the basis-set calculations, the electron-charge densities at the nucleus obtained using the Hiller–Sucher–Feinberg operator are about 50 times more accurate than the values obtained using the δ-function operator. In the numerical correlation calculations, the spin densities at the nucleus obtained for Li, C, N, O, and F using the Hiller–Sucher–Feinberg operator converge faster with the size of the orbital space than those obtained using the δ-function operator, and for Be and B, the two spin-dependent operators perform about equally well.