Atomic relaxation and electronic redistribution of LaAlO3(001) surfaces

Density functional theory has been used to study the atomic and the electronic structures of LaAlO3 (001) surface which has two possible terminations, namely LaO- and AlO2 -terminations. Atomic structure, Mulliken charge and the density of states of the two surfaces have been calculated, respectively. The displacement of different ions, deviated from their crystalline sites, can result in the formation of surface rumpling. The rumpling of LaO plane is larger than that of AlO2 plane in the both surfaces. The first-principle numerical results indicate that different shifts in the total density of states with the two terminations could lead to different characteristics of surface conduction. In addition, surface thermodynamic stability is explored, and it is found that the LaO-terminated surface might be more stable and mixed surface with LaO- and AlO2 -terminations is forbidden. (c) 2007 Elsevier B.V. All rights reserved.