There are several semi-empirical methods in Gaussian 9 software. The most common semiempirical quantum chemistry is Neglect of Diatomic Differential Overlap, Complete Neglect of Differential Overlap (CNO), and Intermediate Differential Overlap (INDO, MINDO) . They are in the Zero Differential Overlap (ZDO) method group, disregarding all two-electron integrals . A semi-empirical model benefits results and approximations derived from experiments to improve the performance of the model . Most semi-empirical methods benefit only the s-and p-orbitals with Staler-type orbitals . The other advantages of semi-empirical methods are that they are inexpensive and time-saving. They have pre-calculated data as a part of the program, which can guide them in solving the Schrodinger equation. Semi-empirical methods are better for a prominent structure with more than 1000 atoms . The local density function, Hartree Fock, results in better accuracy for a 100-atom system . Semi-empirical methods are rooted in the Hartree-Fock model and take only valence electrons for granted. In the engine, GTOs are used, allowing for molecular mechanics, semi-empirical methods, Hartree Fock model, post-Hartree-Fock methods, DFT and molecular modelling .