A program developed to calculate multidimensional Franck-Condon factors including Duschinsky effects is described and used to simulate the vibrationally resolved photoelectron spectra Of S2O- combining with ab initio molecular orbital calculations. Geometry optimizations and harmonic vibrational frequency calculations have been performed on the (X) over tilde (1)A' state Of S2O and (X) over tilde (2)A" state of S2O-. Franck-Condon analysis and spectral simulations were carried out on the first photoelectron band Of S2O-. The simulated spectra obtained by using B3LYP/6-311+G(3df) are in excellent agreement with the experiment. In addition, the accurate equilibrium geometric parameters, r(ss) = 0.1996 +/- 0.0005 nm and r(so) = 0.1514 +/- 0.0005 nm, of the (X) over tilde (2)A" state of S2O-, are deduced by employing an iterative Franck-Condon analysis procedure in the spectral simulation. Furthermore, the well-resolved theoretical spectrum is derived by improving the resolution of photoelectron spectra in simulations. (c) 2006 Elsevier B.V. All rights reserved.