First principles study of the diatomic charged fluorides MF~(+-),M=Sc,Ti,V,Cr,and Mn

摘要

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 [C.Koukounas,S.Kardahakis,and A.Mavridis,J.Chem.Phys.120,11500 (2004)],we have also examined the ground (X ~1SIGMA~+) and the first excited state (a 3A) 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~2DELTA 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.