Density functional calculations of photoionization with an exchange-correlation potential with the correct asymptotic behaviour

Abstract

The effect of the choice of the exchange correlation potential on the cross section and asymmetry parameter profiles is analysed. The VWN potential is compared with respect to the LB94, which displays the correct Coulomb tail. The effect of the two possible choices of the electron configuration (ground state, GS, or transition state, TS) is also considered. The comparison with respect to the experimental data shows that in the outer-valence region the VWN TS and the LB94 GS are the best choices for first-row hydrides and N2 , while for core ionization LB94 GS performs much better. The discrepancies in the second-row hydrides are not recovered by the LB94 potential, and are ascribed to the screening effect which can be taken into account by a time-dependent extension of the theory. Because of accuracy and computational economy, LB94 GS appears to be a decidedly superior choice in comparison with the VWN TS potential.