On the R2PI spectrum of AgNH3: a theoretical study of the quasidegeneracy of the first excited states

The electronic ground state and the three first excited states of AgNH3 hav e been investigated theoretically. At the ab initio CASPT2 level, there isa quasi-degeneracy of the C-3v minima of the (2)A(1) and E-2 excited states (D-e = 1.38 and 1.40 eV, respectively). While the E-2 state displays a clea r Ag(5p(pi)) + NH3 character, the nature of the (2)A(1) is more subtle, wit h both charge transfer and Rydberg characters. Semi-empirical introduction of the spin-orbit coupling enables the interpretation of a few features of the intricated R2PI spectrum. (C) 2000 Elsevier Science B.V. All rights res erved.