Comparison of different hybrid DFT methods on structural, spectroscopic, electronic and NLO parameters for a potential NLO material

Abstract

The molecular geometrical, vibrational frequency, molecular static polarizability and hyperpolarizability parameters, as well as HOMO-LUMO energies of 4-Aminopyridinium monophthalate (4-APMP) as potential nonlinear optical (NLO) material in the ground state were examined using hybrid GGA, meta-GGA, range-separated hybrid and long-range (LR) corrected models (B3LYP, B3PW91, M062X, HSEh1PBE, CAM-B3LYP, LC-BLYP and ωB97XD levels of density functional theory) with 6-311G(d,p) basis set in order to analyze the effects of different percentage of HF exchange. TD-DFT computations with the PCM (polarizable continuum model) within methanol solvent based on implicit/explicit model and gas phase in the excited state were employed to investigate UV–vis absorption and fluorescence emission wavelengths. Furthermore, by regarding the potential energy distribution (PED), a detailed vibrational study was fulfilled by using VEDA program. Experimental values of structural and spectroscopic parameters of 4-APMP were used to display the effects of the different theoretical methods on the spectroscopic and structural properties. To display the agreement and accuracy of among selected DFT levels and experimental data, the linear correlation coefficients (R2), mean absolute deviation (MAD), overall mean percent deviation (MPD), optimal scaling factor (λ) and overall root mean square (RMS) deviation for structural and vibrational frequency parameters were presented. The NLO parameters indicated that 4-APMP exhibits significant molecular nonlinearity.