Phaseshifts, total elastic cross sections and resonances in Ar-Ar scattering

Abstract

The authors have performed systematic quantal calculations of Ar-Ar elastic scattering events using accurate pair potentials. Specifically, they have calculated a large number of partial wave phaseshifts, total cross sections and resonance energies over a range covering most of the glory region. The cross sections from two accurate potentials are compared over one glory oscillation and over a region including several shape resonances. The resonance energies obtained from these two potentials also are compared. The authors discuss the inappropriateness of using Levinson's theorem to define the absolute scale of the phaseshifts for realistic atomic potentials. As an alternative, the authors define an 'absolute phaseshift' that explicitly accounts for the difference in phase between the true wavefunction and its free particle counterpart.