Hartree-Fock calculations of electronic structure of (110)-surface of rutile TiO2:: Comparison of single (2D) and periodic (3D) slab models

Two different slab models are used in calculations of the surface phenomena: two-dimensional (2D) single (isolated) slab model (with 2D periodicity) and three-dimensional (3D)-slab model (with slabs, periodically repeated along the normal to the surface). Here we present the investigation and comparison of these two models basing on calculations of the (110) rutile surface within the same computational scheme (Hartree-Fock linear combination of atomic orbitals approach). The convergence of calculated surface energy and Fermi level is studied with the change of slab thickness and interslab vacuum gap using both pseudopotential and all-electron calculations. It is found that Durand-Barthelat pseudopotentials with diffuse d-functions on Ti atoms lead to the incorrect results for surface energy and Fermi level of 3D-slab model. Inclusion of the core electrons in 3D-slab calculations and the use of the 2D-supercell approach allow obtaining surface energy in quantitative agreement with that obtained in 2D-slab all-electron calculations. (C) 2003 Wiley Periodicals, Inc.