An iterative franck-condon analysis procedure for the determination of ionic geometries for H2O and H2S

Abstract The pattern search optimization procedure is applied to a Franck-Condon analysis method with the use of the formulation proposed by Kupka and Cribb for evaluating vibrational overlap integrals [H. Kupka and P.H. Cribb, J. Chem. Phys., 85 (1986) 1303; H. Kupka and G. Olbrich, J. Chem. Phys., 80 (1985) 3163]. The method was applied to three different ionization processes accompanied by small to large changes in molecular geometry. It was found that ionic geometries thus deduced for transitions with small structural changes agree well with observation. However, the agreement is poor for transitions with large geometric changes although the method can still account for the observed vibrational intensity distributions to a certain extent. In addition, properties of the pattern search method as well as Kupka and Cribb's formulation for Franck-Condon analyses are discussed.