Condensed Matter, abstract
cond-mat/9702198

From: David Vanderbilt <dhv@physics.rutgers.edu>
Date: Fri, 21 Feb 1997 10:50:42 -0500   (46kb)

First-principles theory of structural phase transitions for perovskites: competing instabilities

Authors: David Vanderbilt, W. Zhong (Department of Physics and Astronomy, Rutgers University)
Comments: 21 pages, with 3 postscript figures embedded. Uses REVTEX and epsf macros. Also available at this http URL
Subj-class: Materials Science

We extend our previous first-principles theory for perovskite ferroelectric phase transitions to treat also antiferrodistortive phase transitions. Our approach involves construction of a model Hamiltonian from a Taylor expansion, first-principles calculations to determine expansion parameters, and Monte Carlo simulations to study the resulting system. We apply this approach to three cubic perovskite compounds, SrTiO3, CaTiO3, and NaNbO3, that are known to undergo antiferrodistortive phase transitions. We calculate their transition sequences and transition temperatures at the experimental lattice constants. For SrTiO3, we find our results agree well with experiment. For more complicated compounds like CaTiO3 and NaNbO3, which can have many different structures with very similar energy, the agreement is somewhat less

Paper: Source (46kb) , PostScript , or More Options