Atomistic simulation of ferroelectric–ferroelastic gadolinium molybdate

Gadolinium molybdate Gd$_{2}$(MoO$_{4}$)$_{3}$ orthorhombic ferroelectric ferroelastic ($\beta'$-phase) is simulated by the method of interatomic potentials. The simulation is performed using the GULP 4.0.1 code (General Utility Lattice Program), which is based on the minimization of the energy of the crystal structure. Parameters of the gadolinium–oxygen interatomic interaction potentials are determined by fitting to the experimental structural data and elastic constants by a procedure available in the GULP code. Atomistic modeling using the effective atomic charges and the system of interatomic potentials made it possible to obtain reasonable estimates of structural parameters, atomic coordinates, and the most important physical, mechanical, and thermodynamic properties of these crystals. Temperature dependences of the heat capacity and vibrational entropy of the crystal are obtained. The calculated parameters of gadolinium–oxygen interaction potentials can be used to simulate more complex gadolinium-containing compounds.