title: CH5+: chemistry's chameleon unmasked.
abstract: The nuclear vibrational wave function and zero-point vibrational energy of CH5(+) are calculated using quantum diffusion Monte Carlo techniques on an interpolated potential energy surface constructed from CCSD(T)/aug'-cc-pVTZ ab initio data. From this multidimensional wave function, the vibrationally averaged rotational constants and radial distribution functions for atom-atom distances within the molecule are constructed. It is found that the distributions of all 10 H-H distances are bimodal and identical. The radial distribution functions obtained for the five C-H distances are also identical, but unimodal. The three rotational constants were found to be 3.78, 3.80, and 3.83 cm(-1). These values indicate that the ground state of CH5(+) is significantly more symmetric than its global minimum energy structure. We conclude that the zero-point motion of CH5(+) renders all five protons equivalent in the ground state and precludes the assignment of a unique structure to the molecule.
authors.affiliation: School of Chemistry, University of Sydney, NSW 2006, Australia.
authors.forename: Keiran C
authors.initials: KC
authors.lastname: Thompson
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Crittenden
authors.forename: Meredith J T
authors.initials: MJ
authors.lastname: Jordan