Pressure-induced Structural Phase Transition in Li4Ge
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The structural, dynamic, elastic, and electronic properties of Li4Ge were investigated by means of evolutionary crystal structure prediction in conjunction with first-principles calculations. We find that the ground-state Li4Ge under ambient conditions has a cubic symmetry. Li4Ge undergoes a structural phase transition at about 2 GPa from the cubic P213 phase to the R m phase. The dynamic and mechanical stabilities of P213 and R m were confirmed by phonon and elastic constant calculations. From the calculated elastic constants, we obtained the elastic moduli and discussed their elastic anisotropy effect. Our calculation shows that the P213 structure is brittle while the R mstructure is ductile. The anisotropic properties of R m are more pronounced than those of P213 at ambient pressure. P213-Li4Ge is a narrow band gap semiconductor while the R m phase is a poor metal.
Pressure-induced Structural Phase Transition in Li4Ge.