Theoretical Study of Ca~+-X and Y-Ca~+-X Complexes Important in the Chemistry of Ionospheric Calcium (X, Y = H2O, CO2, N2, O2, and O)

摘要

Optimized geometries and vibrational frequencies are calculated for Ca~+—X and Y—Ca~+—X complexes (X, Y = H2O, N2, CO2,O2, and O), required for understanding the chemistry of calcium in the upper atmosphere. Both MP2 and B3LYP optimizations were performed employing 6-311+G(2d,p) basis sets. In some cases a number of different orientations had to be investigated in order to determine the one of lowest energy, and in cases involving O and O2, different spin states also had to be considered. In order to establish accurate energetics, RCCSD(T) single-point energy calculations were also employed, using aug-cc-pVQZ basis sets. Accurate dissociation energies for the Ca~+—X and X—Ca~+—Y species are derived and discussed. Comparison with available experimental results is made where possible.