Elastic constants of the perovskite RbMnF3using a Born model

The elastic constants of RbMn${\mathrm{F}}_3$ were calculated using a Born model, which consists of electrostatic and Born-Mayer repulsive interactions. This model has two adjustable parameters; these were determined from the equilibrium volume and one of the three second-order elastic constants. Calculated third-order elastic constants agreed reasonably well with experiment. Also calculated were the electrostatic contributions to the first-, second-, and third-order elastic constants of the cubic perovskite structure for several values of ionic charge. Relationships of these constants to those of the NaCl- and CsCl-type structures are given.