A DFT Study on (001) Thin Slabs of SrTiO3 and BaTiO3

In this paper, we studied the relaxation of (001) surface of BaTiO3 and SrTiO3 slabs with two termination surfaces and with 3, 5, and 7 layers thickness for each cases, using density functional theory and generalized gradient approximation for exchange-correlation functional and pseudo potential method. We calculated the slab energy and the rate of expansion and contraction of the layers and compare them for different thicknesses. Band structure and density of states for these slabs and for BaTiO3 and SrTiO3 bulk were computed to find out the variation of band gap with respect to slab thickness. It is found that in comparison with bulk, in TiO2 slabs of both materials gap size decreases while in SrO and BaO slabs it increases.