AB-INITIO PREDICTIONS OF THE ZERO-FIELD SPLITTINGS AND THE SINGLET-TRIPLET TRANSITION STRENGTHS FOR THE (A)OVER-TILDE3A2(T1)[-(X)OVER-TILDE1A1(S0), N-]PI-ASTERISK TRANSITION OF SELENOFORMALDEHYDE

The energy levels of the lower valence and Rydberg states of selenofor maldehyde, CH2Se, have been calculated by the SCF/CI method. Wavefunct ions for the ROHF (restricted open shell Hartree-Fock) states were obt ained with the Binnings-Curtis double-zeta basis set, augmented with R ydberg and polarization functions. Configuration interaction was appli ed to the parent configurations, PCMO (parent configuration molecular orbital). Oscillator strengths were evaluated for the allowed electric dipole transitions by the RPA (random phase approximation), and SOPPA (second-order polarization propagator approximation) methods. The spi n-orbit contribution to the zero field splitting of the first triplet state, 3A2(n,pi) as well as the oscillator strengths to the three spi n components were calculated by perturbation theory. These calculation s predict that the S(x), S(y), and S(z) components are shifted by -96. 091, -96.707, and +29.167 cm-1, respectively, from their unperturbed p osition. The oscillator strengths for the three components f(x), f(y), and f(z) of the 3A2(n,pi) <-- 1A1(g.s.) transition were calculated t o be 3.45 X 10(-7), 1.15 X 10(-7), and 173.0 X 10(-7).