VIBRATIONAL SPECTRAL INVESTIGATION OF NONLINEAR OPTICAL L-ASPARAGINE?L-TARTARIC ACID: A COMBINATION OF EXPERIMENTAL AND THEORETICAL STUDY

L-Asparagine?L-Tartaric (LAsT) acid a second order nonlinear optical (NLO) material was studied in-depth by using vibrational spectra and density functional theory (DFT). The Fourier transform infrared (FT-IR) spectrum was recorded in the range 4500 ? 500 cm-1. Meanwhile, the DFT computations are performed at B3LYP/6-31G (d, p) level to derive equilibrium geometry, vibrational wavenumbers and first hyperpolarizability, and the scaled theoretical wavenumbers are also shown to be in good agreement with experimental data. The nonlinear characteristic and thermal stability of the crystal were also investigated.