First-principles prediction of a metastable crystalline phase of Ga with Cmcm symmetry
M de Koning and A Antonelli and DAC Jara, PHYSICAL REVIEW B, 80, 045209 (2009).
We report on evidence for the existence of an unknown metastable crystalline phase of gallium by the combination of classical molecular- dynamics (MD) simulations and density-functional theory (DFT) calculations. The MD simulations, based on a modified embedded-atom potential, reveal the unknown crystalline form through a first-order phase transition originating from the Cmca symmetric alpha-Ga phase under hydrostatic tension. Subsequently, the DFT calculations using two different generalized-gradient approximation functionals are employed to verify its stability and determine its electronic structure. The structure of the orthorhombic phase is described by symmetry group Cmcm and shows a dimer arrangement resembling the alpha-Ga phase. A first- order phase transition from alpha-Ga to the unknown phase is estimated to occur at -1.3 GPa.
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