First-principles study on tetragonal BaTiO3 ferroelectric
四方相BaTiO3铁电性的第一性原理研究

Based on the generalized gradient approximation (GGA), the total-energy, overla p populations and valence charges in the case of Ti atoms moving along c axis in cubic and tetragonal phases were calculated by using ultrasoft pseudopotentials ( USP) plane wave method. It was demonstrated that the energy of tetragonal BaTiO 3 was the lowest when Ti atoms move along the c axis by up to 0.012nm, an d t he sponta neous polarization was 0.261C/m2 , which was consistent with experimental res ult s. Moreover, it was also confirmed that the ferroelectric stability of BaTiO 3 could be attributed to the orbital hybridization of 2p orbit of oxygen atom and 3d orbit of Ti atom.