Linear and cyclic (HCN)n clusters: A DFT study of IR and Raman spectra

The electronic structure, and the IR- and Raman-spectroscopies of (HCN)n clusters are discussed. DFT is employed in all calculations both in its standard framework and including the solvent effect. Both linear and cyclic structures are optimized. The linear structures are local minima, both with and without the solvent effect. The spectra calculated with the latter present a faster convergence than standard calculations. The predicted spectra agree generally with previous theoretical and experimental results, mainly when considering the solvent effect. Estimates of the IR spectrum of the liquid HCN, and of the gas-phase Raman spectrum are also reported.