Comparing the electric field gradient at chlorine from two-centre and one-centre wavefunction expansion calculations on HCl

Abstract

A one-centre expansion wavefunction, electric field gradient, OCE-EFG, is compared with the effective field gradients from accurate two-centre expansion wavefunctions, TCE-EFG. The OCE-EFG is shown to be accurate; it is computationally economical. Guseinov's formula, for expanding elliptical coordinates as the product of two Legendre polynomials on different centres, is used to evaluate the two-centre integrals over Slater type orbitals, STOs.