Abstract
We present a theoretical ab initio investigation of the low-energy valence Photo Electron (PE) spectrum of NSCN, a novel thiazyl compound recently synthetized, by using many-body post-SCF electronic structure methods. To account for correlation and relaxation effects neglected within the Koopmanns' theorem approximation, we used the SAC/SAC-C. I. theory in calculating the lowest ionization energies. Correlation effects are quite important to reliably understand the recorded PE intensity of NSCN. We are able to propose a different assignment of the entire outer valence PE spectrum of NSCN which seems more consistent and in better agreement with the experiment. We also discuss similarities and differences in the ionization energies of NSCN and closely related molecules (cyanogen and thiazyl halides).