Investigation of the structural, geometric, spectroscopic, and nonlinear optical properties of the L-asparaginium picrate complex

The optimized molecular geometry, vibrational frequencies, and 1 H and 13 C NMR spectra of the L -asparaginium picrate (LASP) complex were calculated using HF and B3LYP methods with the 6–31 G(d,p), 6–311 G(d,p), and 6–311 + + G(d,p) basis sets within the framework of density functional theory (DFT). DFT calculations were performed to investigate the nonlinear optical (NLO) properties of LASP. The results indicate that L -asparaginium picrate is a promising nonlinear optical material with high second harmonic generation (SHG) efficiency. Furthermore, Natural Bond Orbital (NBO) analysis was carried out to examine bond strengths, molecular stability, hyperconjugative interactions, and intramolecular charge transfer (ICT) within the molecule.