THEORETICAL INVESTIGATIONS ON MOLECULAR STRUCTURE, HOMO, LUMO, NBO ANALYSIS AND HYPERPOLARIZABILITY CALCULATIONS OF MONO AND EXTENDED-TETRATHIAFULVALENES (MONO/EX-TTFS)

The optimized molecular structure of (Mono/ex-TTFs) 1-4 has been investigated theoretically using Gaussian 09 software package. This theoretical calculation was carried out by density functional theory (DFT) using B3LYP with 6-31G (d,p) basis set. The stability of the molecule arising from hyper-conjugative interaction and load delocalization has been analyzed using NBO analysis. The HOMO and LUMO energies were also evaluated for these molecules to demonstrate the chemical stability. First and second hyperpolarizability are calculated in order of their role in non-linear optics. Molecular electrostatic potential and all other calculations were performed by the same method cited above. Keywords: tetrathiafulvalenes; density functional theory; computational chemistry; electronic structure; quantum chemical calculations