Complex Gaussian-type basis functions in the calculation of resonance energies and widths

Abstract

Basis set calculations of the energies and widths of several resonances in electron scattering by a one-dimensional model potential are carried out using real basis sets that are augmented with various choices for a long-range complex Gaussian-type function. The results show that neither the form of the complex basis function nor the behavior of the trial wave function near the origin are important for obtaining accurate results. In fact, excellent results are obtained with a modest basis set of real bound functions augmented with a single complex Gaussian orbital when the complex exponential parameter is chosen by a stationary condition and the calculation is stabilized with respect to the bound function exponential parameter.