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.
Yao
Yansun
Y
Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, K1A 0R6, Canada.
Klug
Dennis D
DD
Sun
Jian
J
Martonák
Roman
R