Study of electro-optical behavior of nematic liquid crystal p- butoxybenzylidene, p-heptylaniline (BBHA) under applied electric field by using density functional theory

Variations in the nonlinear optical behavior of nematic liquid crystal p-butoxybenzylidene p-heptylaniline (BBHA) under applied electric fields within the range of 0.001–0.007 a.u. were investigated in this communication utilizing two functionals B3LYP and CAM-B3LYP with the 6311++G(d, p) basis set. In both functionals, the dipole moment, anisotropic polarizability, molar refractivity (MR), order parameters, and hyperpolarizability exhibit irregularities at the applied field E = 0.005 a.u. The hyperpolarizability shifts significantly, and the electronic reactivity parameters are irregular in this applied field by CAM-B3LYP functional. B3LYP functional displays the same tendency with applied field fluctuation within the 0.001–0.007 a.u range. TDDFT calculations employing the long-range CAM-B3LYP functional were performed to explain the large hyperpolarizability at E = 0.005 a.u. The second-order NLO responses qualitatively explain the switching time of BBHA liquid crystals. The irregularity at applied field E = 0.005 a.u. was verified using thermodynamical parameters.