Collect. Czech. Chem. Commun. 2005, 70, 1035-1054

Numerical Methods for the Evaluation of the Löwdin α-Function

Nemanja Sovic and James D. Talman*

Department of Applied Mathematics and Centre for Chemical Physics, University of Western Ontario, London, Ontario, Canada N6A 5B7


The problem of expanding an angular momentum wave function centered at one point in terms of angular momentum wave functions centered at another point is analysed. The emphasis is on obtaining methods that can be applied to functions that are defined numerically, in contrast to analytic methods. Three numerical approaches are described, and it is found that one leads to extremely accurate results. The question of the rate of convergence of the resulting series is discussed, and results of the application of the expansion to the calculation of nuclear attraction three-center integrals, and electron-electron four-center integrals are presented.

Keywords: Gaussian; Orbitals; Slater orbital; Hartree-Fock; Wave function; Numerical methods; Quantum chemistry.

References: 14 live references.