Comparative computational analysis of electronic structure, MEP surface and vibrational assignments of a nematic liquid crystal: 4-n-methyl-4´-cyanobiphenyl

The homologues of 4-n-alkyl-4´-cyanobiphenyl liquid crystal series constitute an important class of materials because of their technology development applications. The first member of this series namely, 4-n-methyl-4´-cyanobiphenyl is reported to be a pure nematic liquid crystal. The molecular geometry of this nematogen has been optimized by ab-initio HF/6-31G(d, p) as well as DFT B3LYP/6-31G(d, p) methods using GAMESS programme. The molecular electrostatic potential surface has been scanned with 0.001 electron/bohr3. Molecular and thermodynamic properties such as total energy, dipole moment, entropy, enthalpy, Gibbs free energy, HOMO and LUMO energies have been calculated. Further, vibrational assignments of 4-n-methyl-4´-cyanobiphenyl molecule have been carried out. A computational analysis of results obtained by ab-initio and DFT techniques has been discussed in the light of experimental observations available in literature.