This potential can be inserted in Equation for the calculation of Kohn-Sham potential. The LDA method has been found to provide an accurate result for the systems, where charge density varies slowly. However, in strongly correlated systems, where independent particle picture breakdown, the LDA method show very inaccurate results . For example, LDA prediction shows that transition metal oxides XO (X=Fe, Mn, Ni) can be either metal or semiconductor, while in the real picture, they are only Mott insulators. Furthermore, LDA does not account for the van der Waal bonding, which provides a poor description of hydrogen bonding. The mentioned as well as other limitations of LDA method, motivated to develop the other approximation such as generalised gradient approximation.