mtrl-th/9411005
Paper: mtrl-th/9411005
From: weiqing@physics.rutgers.edu (Weiqing Zhong)
Date: Wed, 16 Nov 94 19:12:53 EST
Title: Competing structural instabilities in cubic perovskites
Author: W.~Zhong and David Vanderbilt (Rutgers University)
Comments: 12 Pages Latex, 3 Postscript figures
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.
(N.B.: delivery types and potential problems)