First-Principle Study of Ca₃Y₂Ge₃O₁₂ Garnet: Dynamical, Elastic Properties and Stability under Pressure

Abstract

We present here an ab initio study under the framework of the Density Functional Theory of the Ca3Y2Ge3O12 garnet. Our study focuses on the analysis of the structural, electronic, dynamic, and elastic properties of this material under hydrostatic pressure. We report information regarding the equation of state, the compressibility, and the structural evolution of this compound. The dynamical properties and the evolution under pressure of infrared, silent, and Raman frequencies and their pressure coefficients are also presented. The dependence on the pressure of the elastic constants and the mechanical and elastic properties are analyzed. From our results, we conclude that this garnet becomes mechanically unstable at 45.7 GPa; moreover, we also find evidence of soft phonons at 34.4 GPa, showing the dynamical instability of this compound above this pressure.

Keywords

• ab initio
• garnet
• equation of state
• elasticity
• phonons
• Raman