Theoretical and Experimental Solid State Physics

Density Functional Theory has proved to be a fast and efficient method for calculating various properties of solid insulating materials. From our studies, we have observed that calculations of the structural and electronic properties of alkali metal hydrides LiH, NaH, KH, RbH and CsH) and alkaline earth metal hydrides (BeH2, MgH2, CaH2, SrH2 and BaH2) reveal the exact problem with the description for these compounds within PBE formulation of generalized gradient approximation (GGA), which is our principal focus.Generally, for the hydrides accurate calculation of the band gap requires computationally extensive approach as GW method or time-dependent DFT. In this work, a new and more efficient method, GGA + U, which significantly improves the description of the electronic structure in DFT has been used; thus, in this proposed method, our results were in agreement with other theoretical and experimental results obtained by other investigators. GGA+U approach is based on the Hubbard model applied for exchange-correlation function to hydrogen atoms, even though the metal hydrides are not strongly correlated materials.