Vibrational analysis for short carbon chains with alternating and cumulenic structure

Calculations of the IR and Raman spectra of molecules containing linear carbon segments are reported. H-C2n-H (n = 1, 2, 3, 4, 5) and H2-C2n-H2 (n = 1, 2, 3, 4, 5) were choosen to model the alternating and the cumulenic structures, respectively. Geometry optimization and force constant calculation were done on the ab initio Hartree-Fock level using Dunningʹs double-ζ basis set with polarization. The frequencies were scaled by Pulayʹs method. IR- and Raman-intensities were obtained by calculating dipole- and polarizability derivatives, respectively.