Atomic displacements at a Sigma 3(111) grain boundary in BaTiO3: A first-principles determination - art. no. 060101

The atomic and electronic structure at a Sigma3(111) grain boundary in BaTi O3 was investigated by the first-principles band-structure DMol(3) total en ergy/atomic force method within the local-density approximation. Our first- principles calculations indicate an expansion of the nearest Ti-Ti spacing across the grain-boundary plane and a contraction of the nearest BaO-BaO sp acing, in excellent agreement with the experimental observation of Jia and Thust [Phys. Rev. Lett. 82, 5052 (1999)]. An additional attraction of oxyge n atoms to the nearest Ti atom pairs, as well as a small volume expansion, are also found at the grain boundary. The atomic displacements were explain ed with an electronic structure analysis.