Evolution of structure in CH5 + and its deuterated analogues.

Diffusion Monte Carlo simulations are used to investigate the effects of deuteration on the fluxionality of CH(5)(+) or CD(5)(+), using an ab initio potential surface, developed by Jin, Braams, and Bowman [J. Phys. Chem. 2006, 110, 1569]. We find that partial deuteration quenches the fluxional behavior. The spectral consequences are also investigated. We find that, while CH(5)(+) and CD(5)(+) are nearly spherical tops, partial deuteration breaks the rotational symmetry and the mixed isotopologues are generally better characterized as symmetric tops. In addition, we investigate the effects of deuteration on the low-resolution vibrational spectrum and anticipate that signatures of this delocalization will be observable in the vibrational spectrum.