Ab-initio electronic calculations of the directions, frequencies, and magnitudes of transition dipole moments of sub-molecular vibrational modes in chiral smectic liquid crystals

Ab-initio density functional theory (DFT) level computations have been carr ied out using the B3LYP/6-31G* and 6-31G** basis set to calculate the direc tions, frequencies, and magnitudes of transition dipole moments of the sub- molecular vibrational modes in several ferroelectric liquid crystal (FLC) c ompounds. Polarized infrared spectroscopy of aligned smectic liquid crystal materials also has been carried out to probe the orientational conformatio ns of several sub-fragments of ferroelectric liquid crystal molecules. It t urns out that thc directions of vibrational transition moments, which deter mine primarily the polar plots of the absorbance patterns, are considerably different from those of molecular bonds and are influenced by major atomic interactions, such as hydrogen bondings. The calculated vibrational freque ncies are in very good accord with the experimental values.