Computational study of (CH3[sbnd]C[tbnd]N)n (n = 1 − 5) oligomers using Density Functional Theory method

Abstract

We studied cyclic and ladder type hydrogen bonded oligomers of acetonitrile using Density Functional Theory method. The structural parameters, interaction energies and vibrational frequencies for the monomer at B3LYP/aug-cc-pvdz level are in agreement with the available experimental determinations. In case of cyclic oligomers, five modes are blue and three red shifted than the corresponding modes in monomer. For the ladder oligomers, six modes are blue and three red shifted than the monomer. The finite field method has been used to obtain hyperpolarizabilities for the oligomers. The dipole moment of ladder dimer and tetramer is found to be zero due to the centrosymmetry. The β values are close to zero for both types of oligomers whereas γ values are increased with an increase in number of monomeric molecules in oligomers.