Effect of new DFT methods on spectroscopy and NLO analysis of 2-Bromo-5-nitrothiozole and nitrosodimethylamine

The present study reports the effect of new DFT methods introduced in Gaussian 16 viz B2PLYP, B2PLYPD, DSDPBEP86, and MPW2LPLYP on spectroscopy and nonlinear optical (NLO) properties. The 2-Bromo-5-nitrothiozole and nitrosodimethylamine are considered for the study. In addition to new methods, old DFT, MP2, and HF methods are also considered. The spectroscopic study of geometrical parameters, vibrational, electronic absorption spectra, and HOMO–LUMO gap with their molecular orbitals have been reported. The geometrical parameters such as optimized energy, dipole moment, bond length, and angles have been reported. The diffuse and polarized basis set 6–311 + + G(d,p) has been used for the study. The first- and second-order hyperpolarizabilities have also been reported for both molecules at all methods. This study shows that these two molecules are responsive to nonlinear optical (NLO), which reflects its enhanced applicability in the development of photonic devices. The finite field approach has been applied for calculating first ( β ) and second hyperpolarizabilities ( ϒ ) respectively. The HOMO–LUMO energy gap of nitrosodimethylamine is found to be greater than that of 2-Bromo-5-nitrothiozole. Gaussian16 program package has been used for all these calculations.