Ab-initio investigation of the octahedra rotation in strained Ruddlesden-Popper(RP) phases*

This talk presents the result of an ab-initio study of Ruddlesden-Popper(RP) phases for $Sr_{n+1}Ti_{n}O_{3n+1}$($n = 1, 2, 3, \infty$) compounds with the density functional theory(DFT). In particular, we present results for the relation between octahedral rotations and external strains. We find that rotational reconstructions are energetically favorable under nonzero in-plane strains with a critical strain that depends on both $n$ and rotational configurations. We also explore the relative stability of RP phases with different values of $n$ under epitaxial conditions.