A Comparative Study of Different DFT Functionals on the Nonlinear Optical (NLO) Properties of Some NLO Prototypes

Abstract

he present study spotlights the fundamental insights about four different classes of functionals and their efficacy to calculate the nonlinear optical (NLO) and linear properties. For this study, urea and (p-NA) para-nitroaniline molecules are used up as reference organic molecules. For comparative analysis, there is a dire need of such database to be utilized by the researchers. We have reported a range of functionals including hybrid (B3LYP, PBE1PBE, BHandHLYP), meta-hybrid (M06, M06-2X, M06-HF, M06-L), long-range corrected (CAM-B3LYP, LC-BLYP, LC-B97D, LCB97D3) along with dispersion correction (ωB97, ωB97X, ωB97XD, HSEH1PBE). These groups are evaluated and their efficiency to calculate linear and NLO properties is graphically compared with each other. NLO properties including anisotropic and linear isotropic polarizabilities, dipole moment, second- and third- order polarizabilities were analysed using their corresponding groups and there functionals. The presented results will help researchers to compare their calculations for the properties of NLO in different species. The current study highlights the importance of different functionals and their methods to be employed on various organic and inorganic species to study and evaluate their hyperpolarizabilities. The dipole moment of urea has been found to be 5.14 D which is close to experimentally determined value of 4.56 D. Similarly, the respective experimental and theoretical values of average second order polarizability as calculated by ωB97XD are quite close to each other. Interestingly, similar values of LC-B97D and LC-B97D3 for all the calculated parameters are obtained corresponding to urea and p-NA. A good agreement has been noticed among geometries, total electronic dipole moments and NLO polarizabilities on comparative basis. In addition, the (MEP) molecular electrostatic potential and (FMO) frontier molecular orbital map analyses are executed for the visual insight of charge transfer and predicting the reactive sites. In short, the current work provides significant methods to study the dipole moment, bond lengths, bond angles, static and frequency dependent second order and third-order polarizabilities. linear isotropic and anisotropic polarizabilities. Hence, the present results will attract the scientific community to compare their experimental work on various organic species with our results of urea and p-NA. These compounds are widely used as reference species in experimental and theoretical appraisal in the field x of nonlinear and linear optics. The current investigation will evoke scientific interest regarding the promising comparison of NLO properties in various organic species which can be beneficial in modern hi-tech applications.