AB-INITIO PREDICTIONS OF VIBRATIONAL FREQUENCIES FOR CATIONIC SPECIES

Predicted vibrational frequencies are reported for 15 small cationic species from Hartree-Fock calculations using the 4-21G and 6-31G* basis sets. Force constants from these calculations were corrected using empirical scale factors taken from a collection of similar neutral molecules. These scale factors reproduce 184 experimental frequencies for the neutral molecules with percent errors of 3.1% and 2.5% for the 4-21G and 6-31G* basis sets, respectively. When these scale factors are applied to the cations, 22 known experimental frequencies are predicted with percent errors of 4.5% and 2.0%, respectively.