Polar P6(3)cm phase as a marginally stable ground-state structure of InMnO3: First-principles study

Abstract

To resolve a dispute associated with the ferroelectricity in hexagonal InMnO3 (h-IMO), we have examined the ground-state structure by exploiting density-functional theory calculations. It is shown that the ferroelectric P6(3)cm phase is marginally stable over the nonpolar P (3) over bar c1 phase for a wide range of the external pressure. However, the computed Kohn-Sham energy predicts an interesting crossover from the polar P63cm state to the nonpolar P3c1 state beginning at a compressive strain of similar to 1%. The partial density of states (PDOS) supports our previous finding that the In 4d-O 2p hybridization is the main bonding mechanism directly related to the manifestation of ferroelectricity in h-IMO. In addition, the computed PDOS does not show any evidence of the In 5s-O 2p orbital overlapping which had been asserted to be the main bonding interaction in the nonpolar P (3) over bar c1 phase. Copyright (C) EPLA, 2013