Molecular-Dynamics Simulation of the Structural Phase Transition in Rb₂CaCl₄

Authors

D. P. Billesbach, University of Nebraska-LincolnFollow
P. J. Edwardson, University of Nebraska-Lincoln
John R. Hardy, University of Nebraska-LincolnFollow

Date of this Version

1-1-1988

Comments

Published in Physical Review B Volume 37, Number 1, 1 January 1988. Copyright © 1988 The American Physical Society. Used by permission.

Abstract

We have simulated the structural phase transition of one member of A₂BX₄ layered perovskite-like compounds, Rb₂CaC1₄. This family of compounds may be thought of as being constructed from normal perovskite unit cells but with a different stacking arrangement. In recent months, this structural family has become extremely important since it is the parent structure from which the new class of high-temperature superconductors comes from. The simulation was done using ab initio potentials with no adjustable parameters. Our calculations show a specific-heat anomaly at 400 K which corresponds to an observed pseudorotation of the CaCl₆ octahedral group. This rotation is similar to the structural phase transitions observed in the perovskite-structure family. We also postulate a dynamically disordered high-temperature structure for this compound.