Investigation of the potential energy surfaces for the ground (X)over-tilde(1)A(1) and excited (C)over-tilde(1)B(2) electronic states of SO2

The stationary points along the dissociation path are investigated by means of high-level ab initio methods and the reliability of different methods i s discussed. The multi-reference AQCC method using the ANO-type basis set i s shown to give geometrical parameters and relative energies in very good a greement with experiment. At this level of theory, the (C) over tilde B-1(2 )((1)A') state has an asymmetrical equilibrium geometry and double-minimum potential with a barrier of 170 cm(-1), in good-agreement with experimental data. (C) 1999 Elsevier Science B.V. All rights reserved.