Simulation of the Polarizable-Ion Dynamics of Rb₂ZnCl₄

Authors

P. J. Edwardson, United States Naval Research Laboratory, Washington, D.C.
John R. Hardy, University of Nebraska-Lincoln

Document Type

Article

Date of this Version

8-1-1988

Citation

Physical Review B (August 1, 1988) 38(4)

Comments

Copyright © 1988, American Physical Society. Used by permission

Abstract

The promotion yet prevention of structural stability in the paraelectric phase of Rb₂ZnCl₄ by ionic polarizability is explored with both constant-lattice and variable-lattice simulations. As many as 168 ions ( 3 x 1 x 2 cells) under periodic boundary constraints are allowed to polarize in nonlinear response to forces which are obtained from the electron-gas model of Gordon and Kim. No assumption about the rigidity of the ZnCl₄^2- ion is made. The cause of polarization catastrophe in linear models is examined, and a cure is implemented via nonlinearity of the dipole moment versus field strength. Among the observations are a soliton and cell-multiplying instabilities against rotations and translations of the ZnC1₄^2- ions.