Ab initio calculation of gas-phase ion mobilities of third period atomic ions in helium

Abstract

The interaction potentials for helium with the ground-state atomic ions of the third row of the periodic table, Na+ to Cl+, and the Si+(4P) excited state have been calculated at the MP4SDTQ/6-311 + G(3df,3pd) level of theory, with and without a counterpoise correction for basis-set superposition. The gas-phase ion mobilities of the atomic ions in helium have been calculated using three-temperature theory from these calculated interaction potentials. Where the atomic ion is a state, various ways of averaging the contribution from the Σ and π molecular states were investigated. In the few cases where experimental measurements are available, there is good agreement between theory and experiment.