2.1.1. Density Functional Theory Calculation

The ground state electronic energy is ascertained by electron density of the compound [33]. The electron density defines the number of electrons, nuclear charge and position of the nuclei in a compound [34]. Variation in electron density yields different ground state energy, and both of these properties are related by density functional theory methods [35]. DFT methods are based on suggestions that electron density can be accurately assumed by the set of specific orbitals using an exchange correlation such as B3LYP [36]. Based on their computational accuracy, DFT methods are a reliable and efficient approach for correct estimation of electronic properties of the compound [37]. The structural geometries of selected compounds were optimized through DFT studies. DFT calculations were executed on Guassian09 program [38] using B3LYPfunctional correlation and 6-31G\* as a basis set [39]. It is a compelling theory to calculate the electronic structure of atoms and molecules. Gauss View 6 was used for visualization of output files [40]. In addition, DFT/B3LYP method was employed for generation of Frontier molecular orbitals (FMOs), electrostatic surface potential map and global and local reactivity of descriptors. After completion of calculations, the output log file was visualized in Gauss View 6 for determination of optimization energy, dipole moment, frequency and polarizability [41].
