Structural relaxation and longitudinal dipole moment ofSrTiO3(001)(1×1)surfaces

Abstract

First-principles calculations are employed to study SrTiO 3 (001) (1ϫ1) surfaces with both SrO and TiO 2 termination. A detailed geometry of the relaxed systems, surface energy, and the individual relaxation energies of the two types of surface are obtained. The longitudinal surface dipole moments are derived from variation of the macroscopic electrostatic potential along the surface normal direction. Pseudopotential-plane-wave calculations are performed in the slab geometry, on both symmetric and asymmetric slabs; the merits and the limits of the latter geometry are discussed. PRB 62 C. CHENG, K. KUNC, AND M. H. LEE

Ab initiocalculations of the atomic and electronic structure ofCaTiO3(001) and (011) surfaces

“…Our calculated inward relaxation of the first-layer oxygen atoms on the CaO-terminated CaTiO 3 (001) surface is in line with previous ab initio studies dealing with BaTiO 3 , PbTiO 3 , and BaZrO 3 (001) surfaces, 32,42,61,62 but contrasts with the outward relaxation of first-layer oxygen atoms on the SrO-terminated SrTiO 3 (001) surface. 7,20,21 According to the results of our current calculations, outward relaxations are found for all atoms in the second layer for both CaO and TiO 2 terminations of the CaTiO 3 (001) surface. Table II shows that the relaxations of the surface metal atoms are much larger than those of the oxygens on both the TiO 2 -and CaO-terminated CaTiO 3 (001) surfaces, leading to a considerable rumpling of the outermost surface plane.…”

“…5 and is larger than the corresponding value for 3 , BaTiO 3 , BaZrO 3 , and PbTiO 3 (001) surfaces. 7,20,21,32,42,61,62 As for experimental confirmation of these results, we are unfortunately unaware of experimental measurements of ∆d 12 and ∆d 23 for the CaTiO 3 (001) surfaces. Moreover, for the case of the SrO-terminated SrTiO 3 (001) surface, existing LEED 24 and RHEED 25 experiments actually contradict each other regarding the sign of ∆d 12 .…”

“…7,32,42,61,62 Our calculated surface rumpling of 7.89% for the CaO-terminated (001) surface is almost five times larger than that of the corresponding TiO 2 -terminated surface, and is comparable with the surface rumpling of 9.54% obtained for the CaO-terminated surface by Wang et al 5 This rumpling is larger than the rumplings obtained in previous ab initio calculations for the AOterminated (001) surfaces of SrTiO 3 , BaTiO 3 , BaZrO 3 , and PbTiO 3 . 7,20,21,32,42,61,62 Our calculations predict a compression of the interlayer distance between first and second planes, and an expansion between second and third planes, for the (001) surfaces. Our value for ∆d 12 of −9.43% on the CaOterminated (001) surface is in a reasonable agreement with the result of −11.43% obtained by Wang et a.…”

“…For the CaTiO 3 (001) surface we are only aware of the work of Wang et al 5 and Zhang et al 6 In contrast, several other ABO 3 perovskite (001) surfaces have been widely studied. For example, ab initio 7,8,9,10,11,12,13,14,15,16,17,18,19,20,21 and classical shell-model 22,23 studies were published for the (001) surfaces of SrTiO 3 . The (001) surfaces of cubic perovskites have also been extensively investigated experimentally.…”

First principle electronic, structural, elastic, and optical properties of strontium titanate

“…[9][10][11][12][13][14][15][16] During the last few decades, the electronic, structural, elastic, and optical properties of SrTiO 3 (STO), as a model of ABO 3 perovskite, have been under intensive investigation both experimentally [17][18][19][20][21][22][23] and theoretically. [9][10][11][12][13][24][25][26][27] But, from a theoretical point of view, a proper description of its electronic properties is still an area of active research. Theoretical computations have had difficulty in predicting the correct band gap energy and other related electronic properties of SrTiO 3 from first principle.…”