First principles study of the diatomic charged fluorides MF±, M=Sc, Ti, V, Cr, and Mn

Abstract

Employing multireference configuration interaction and coupled-cluster methods in conjunction with quantitative basis sets, we have explored the electronic structure of the charged diatomic fluorides MF(+/-), where M=Sc, Ti, V, Cr, and Mn. In addition, and in order to complete our recently published work on the neutral diatomic fluorides MF, M=Ti-Mn, we have also examined the ground (X (1)Sigma(+)) and the first excited state (alpha (3)Delta) of neutral ScF. For the entire anionic MF(-) series and the cations ScF(+), VF(+), and MnF(+), no experimental or theoretical results of any kind have been reported so far in the literature. For the charged MF(+/-) sequence we have investigated a total of 43=29(MF(+))+14(MF(-)) states, reporting potential energy curves, energetics, and common spectroscopic parameters. Two are the most interesting conclusions of the present work. (a) The Coulombic binding character of MF(+) cations, i.e., the conformity of their equilibrium description to M(2+)F(-) and (b) the atypical bonding of the MF(-) anions and their surprisingly high dissociation energies (up to 85 kcal/mol for the X (2)Delta state of ScF(-)). Considering the complexities of these chemically "simple" systems, our results on ScF, TiF(+), and CrF(+) are in very good agreement with the limited experimental findings.