Surface relaxation and tilting in SrHfO3 orthorhombic perovskite: Hybrid HF-DFT LCAO calculations

While the upright displacements of the topmost atoms are mainly due to additional distortions of the surface octahedra, the lateral atomic displacements are closely related to changing in surface group tilting. The approach for the analysis of surface octahedron tilting is proposed and applied to the relaxed orthorhombic surfaces of SrHfO3 perovskites. It is shown that the HfO5 group on the HfO2-termianted surfaces undergoes a considerable turn upon relaxation, resulting in alignment of Hf-O-Hf bonds to corresponding pseudo-cubic directions.