The ground singlet and low-lying triplet electronic states of CuF3

A computational study of the structure and properties of the ground and low -lying excited electronic states of the CuF3 molecule is reported in this p aper. Highly sophisticated methods were used, including the coupled-cluster singles and doubles level augmented by a perturbative correction for conne cted triple excitations, and the equation of motion coupled cluster method in the singles and doubles approximation. In agreement with a previous quan tum chemical calculation, the present results predict a T-shaped C-2v equil ibrium geometry for the singlet (1)A(l) state, as expected. The tripler ele ctronic stares of CuF3 were investigated for the first time. The lowest tri pler, (3)A(2)', is only 1700 cm(-1) above the ground 1A(l) state and corres ponds to a trigonal planar D-3h equilibrium structure. The E-3 triplet stat e was found to lie above the (3)A(2)' state by 11 000 cm(-1). (C) 2000 Else vier Science B.V. All rights reserved.