Structural prediction and phase transformation mechanisms in calcium at high pressure.
High-pressure phase transformations of Ca are studied using the metadynamics method to explore the anharmonic free-energy surface, together with a genetic algorithm structural search method to identify lowest enthalpy structures. Disagreement between theory and experiment regarding the structure of Ca in the pressure range 32-119 GPa is partially resolved by the demonstration of different phase transition behavior at 300 K from that at low temperatures. A new lowest enthalpy I4(1)/amd structure is obtained with both methods with an estimated superconducting critical temperature in agreement with experiment.
Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, K1A 0R6, Canada.
Yansun
Y
Yao
Dennis D
DD
Klug
Jian
J
Sun
Roman
R
Martonák