STRUCTURE AND ANISOTROPY OF IONIC ARGON CLUSTERS USING DENSITY-FUNCTIONAL MODELS

Various density functional theory (DFT) approaches are examined in ord er to investigate their performance when describing the general behavi or and the relative energetics of the potential energy surfaces (PES) of Ar-n(+)(X(2) Sigma(+)) systems, with n = 2, 3 and 4. The selected m odellings of correlation forces via DFT treatments show in the present example that the necessary contributions to interaction energies from such forces are rather well described in this way and compare well wi th conventional configuration interaction (CI) calculations and with p erturbative treatments with the same, or similar, initial basis set ex pansions. The present calculations further show the importance of corr elation effects and of exact exchange contributions when modelling PES features of ionic rare gas systems.