Calculations of Electronic Structure and Nonlinear Optical Parameters of 4-Methoxybenzaldehyde-N-Methyl-4-Stilbazolium Tosylate*

The optimized molecular geometry, vibrational frequencies, and gauge including atomic orbital (GIAO) H-1 and C-13 chemical shifts of 4 -methoxybenzaldehyde-N-methyl-4-stilbazolium tosylate (MBST) were calculated using density functional theory (DFT/B3LYP) and the Hartree-Fock (HF) method with the 6-311++G(d,p) basis set. Nonlinear optical (NLO) parameters [mean polarizability (), the anisotropy of the polarizability (Delta alpha), and the mean firstorder hyperpolarizability ()] of the title compound were investigated theoretically. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies of the MBST compound were calculated with the same methods and basis set. Molecular hardness (eta) and electronegativity (chi) were obtained by using the HOMO and LUMO molecular orbital energies. Electronic transitions of the compound were calculated with the time-dependent DFT/B3LYP (TD-DFT/B3LYP) and HF methods. Mulliken, atomic polar tensor (APT), and natural bond orbital (NBO) charges were calculated and compared with each other