Effects of non-adiabatic and Coriolis couplings on the bound states of He(2 ^3S) + He(2 ^3P)

Abstract

The effects of non-adiabatic and Coriolis couplings on the bound states of the He(2 ^3S1) + He(2 ^3Pj) system, where j = 0, 1, 2, are investigated using the recently available ab initio short-range 1, 3, 5Σ+g, u and 1, 3, 5Πg, u potentials computed by Deguilhem et al (2009 J. Phys. B: At. Mol. Opt. Phys. 42 015102). Three sets of calculations have been undertaken: single-channel, multichannel without Coriolis couplings and full multichannel with Coriolis couplings. We find that non-adiabatic effects are negligible for 0−u, 0±g, 1u, 2g, 2u, 3g Hund case (c) sets of levels in the j = 2 asymptote but can be up to 15% for some of the 0+u and 1g sets of levels where near degeneracies are present in the single-channel diagonalized potentials. Coriolis couplings are most significant for weakly bound levels, ranging from 1% to 5% for total angular momenta J = 1, 2 and up to 10% for J = 3. Levels near the j = 1 and j = 0 asymptotes agree closely with previous multichannel calculations based upon long-range potentials constructed from retarded resonance dipole and dispersion interactions. Assignment of theoretical levels to experimental observations using criteria based upon the short-range character of each level and their coupling to metastable ground states produces well-matched assignments for the majority of observations. After a 1% increase in the slope of the 5Σ+g, u and 5Πg, u input potentials near the classical turning point is applied, improved matching of previous assignments is obtained and further assignments can be made, reproducing very closely the number of experimental observations.