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).

DOI: 10.1103/PhysRevB.80.045209

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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