RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A, cilt.88, sa.13, ss.2348-2358, 2014 (SCI-Expanded)
In this study, quantum chemical calculations of geometric parameters, conformational, natural bond orbital (NBO) and nonlinear optical (NLO) properties, vibrational frequencies, H-1 and C-13 NMR chemical shifts of the title molecule [C9H7F5N2O3] in the ground state have been calculated with the help of Density Functional Theory (DFT-B3LYP/6-311++G(d, p)) and Hartree-Fock (HF/6-311++G(d, p)) methods. The optimized geometric parameters, vibrational frequencies, H-1 and C-13 NMR chemical shifts values are compared with experimental values of the investigated molecules. Comparison between experimental and theoretical results showed that B3LYP/6-311++G(d, p) method is able to provide more satisfactory results. In order to understand this phenomenon in the context of molecular orbital picture, we examined the molecular frontier orbital energies (HOMO, HOMO-1, LUMO, and LUMO + 1), the energy difference (Delta E) between E-HOMO and E-LUMO, electronegativity (chi), hardness (eta), softness (S) calculated by HF/6-311++G(d, p) and B3LYP/6-311++G(d, p) levels. The molecular surfaces, Mulliken, NBO, and Atomic polar tensor (APT) charges of the investigated molecule have also been calculated by using the same methods.