International Journal of Scientific Research and Engineering Development

In this study, we investigate the nonlinear optical (NLO) properties of substituted derivatives of 1,3,5‑triamino‑2,4,6‑trinitrobenzene (TATB) using density functional theory (DFT). Emphasis is placed on the first hyperpolarizability (β), a key parameter governing molecular NLO response. A series of electron-donating and electron-withdrawing substituents were introduced at various positions on the TATB ring to assess their influence on molecular geometry, electronic structure, and β values. The B3LYP functional with the 6-311++G(d,p) basis set was employed for geometry optimizations and hyperpolarizability calculations. Results reveal a strong correlation between the nature of the substituent and the enhancement or suppression of NLO properties. Donor-acceptor substituted systems displayed significant intramolecular charge transfer, resulting in markedly increased β values. These findings provide molecular design insights for TATB-based NLO materials and suggest viable structural modifications to optimize optical performance. The study underlines the potential of tailored TATB derivatives in organic optoelectronic applications.