CASSCF BENDING POTENTIAL-ENERGY SURFACES OF SOME LOW-LYING ELECTRONICSTATES OF SI-3 AND THE SI-3(-) ANION IN C-2V SYMMETRY

The bending potential energy surfaces of several electronic states of Si-3 and its anion have been investigated within C-2v point-group symm etry, by using the complete active space SCF method. The investigation is confined to the C-2v --> D-proportional to h path to elucidate the correlations between linear and bent electronic states. The majority of the singlet and triplet states of Si-3 exhibit avoided crossings fo r bending angles of 80-100 degrees. The (1)A(1) ground state and the B -3(2) excited state are very close in energy. Consequently, the (2)A(1 ) negative-ion ground state and the B-2(2) excited state exhibit almos t the same electron affinities. (C) 1998 Elsevier Science B.V.