LAUSR

Abstract On the grounds of a hybrid CCSD(T)/B3LYP/aug-cc-pVTZ anharmonic potential and the use of a variational and variational-perturbational methods, the IR spectra of dicyanodiacetylene C6N2 is revisited in the mid-infrared region up to 4500 cm−1. A position and intensity analysis of our theoretical results allow us to assign the fundamental bands together with their combinations and overtones, in the aforementioned range of frequencies. The pure theoretical results are discussed in relation with the pure experimental data. The main objective of this paper is to give an ‘a priori’ complete IR spectrum of C6N2 which can be used as a guide of the low-intensity bands in areas not completely assigned so far.