An ab initio Study of the $\tilde{X}(^{2}A_{1}$) and $\tilde{A}(^{2}E$) States of $MgCH_{3}$ and $ZnCH_{3}$

Abstract

The ground and first excited states of the recently observed $ZnCH_{3}{^{1}}$ radical and the not yet observed $MgCH_{3}$ radical were studied. The geometries of the ground and first excited state were optimized at the SCF, CISD, corrected CISD, and the ACPF, levels of theory, under $C_{3{v}}$ symmetry constraints. The vertical excitation energies were computed for single and multi-reference ACPF, CISD, corrected CISD, and SCF wave functions, using a dzp basis set, and a up basis set. The results from the $ZnCH_{3}$ study were used as an aid in the assignment of the rotationally resolved electronic spectrum of this $species^{2}$. The implications of these results for the obtainment of the electronic spectra of $MgCH_{3}$ and its cation will be discussed.