Competing structural instabilities in cubic perovskites

W. ~Zhong; David Vanderbilt

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arXiv · mtrl-th/9411005

Competing structural instabilities in cubic perovskites

W. ~Zhong·David Vanderbilt

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Abstract

We study the antiferrodistortive instability and its interaction with ferroelectricity in cubic perovskite compounds. Our first-principles calculations show that coexistence of both instabilities is very common. We develop a first-principles scheme to study the thermodynamics of these compounds when both instabilities are present, and apply it to SrTiO$_3$. We find that increased pressure enhances the antiferrodistortive instability while suppressing the ferroelectric one. Moreover, the presence of one instability tends to suppress the other. A very rich $P$--$T$ phase diagram results.

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W. ~Zhong, David Vanderbilt. 1994-11-17. Competing structural instabilities in cubic perovskites. https://arxiv.org/abs/mtrl-th/9411005

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