Ab initio calculations of the atomic and electronic structure of CaTiO3 (001) and (011) surfaces

Article

关键词: EFFECTIVE CORE POTENTIALS;    GENERALIZED GRADIENT APPROXIMATION;    SCANNING-TUNNELING-MICROSCOPY;    MOLECULAR CALCULATIONS;    SRTIO3(100) SURFACE;    PHASE-TRANSITIONS;    SRTIO3(001);    PEROVSKITE;    1ST-PRINCIPLES;    RELAXATION;   

DOI  :  10.1103/PhysRevB.78.155420

来源: SCIE

【 摘 要 】

We present the results of calculations of surface relaxations, energetics, and bonding properties for CaTiO3 (001) and (011) surfaces using a hybrid description of exchange and correlation. We consider both CaO and TiO2 terminations of the nonpolar (001) surface and Ca, TiO, and O terminations of the polar (011) surface. On the (001) surfaces, we find that all upper-layer atoms relax inward on the CaO-terminated surface, while outward relaxations of all atoms in the second layer are found for both terminations. For the TiO2-terminated (001) surface, the largest relaxations are on the second-layer atoms. The surface rumpling is much larger for the CaO terminated than for the TiO2-terminated (001) surface, but their surface energies are quite similar at 0.94 and 1.13 eV/cell, respectively. In contrast, different terminations of the (011) CaTiO3 surface lead to very different surface energies of 1.86, 1.91, and 3.13 eV/cell for the O-terminated, Ca-terminated, and TiO-terminated (011) surface, respectively. Our results for surface energies contrast sharply with those of Zhang [Phys. Rev. B 76, 115426 (2007)], where the authors found a rather different pattern of surface energies. We predict a considerable increase in the Ti-O chemical bond covalency near the (011) surface as compared both to the bulk and to the (001) surface.

【 授权许可】

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