High-pressure structures of lithium, potassium, and rubidium predicted by an ab initio evolutionary algorithm

Yanming Ma, Artem R. Oganov, and Yu Xie
Phys. Rev. B 78, 014102 – Published 8 July 2008

Abstract

We have extensively explored the high-pressure structures of lithium (Li), potassium (K), and rubidium (Rb) using an ab initio evolutionary algorithm. For Li, an unexpected cubic P4132 structure containing sixfold coordinated lithium atoms and Li3 equilateral triangles was discovered to be stable above 300 GPa. This structure is reported for the first time in the elements and shows charge accumulation in the voids of the structure, rather than within the Li3 triangles. At pressures above the stability field of complex incommensurate phases, the heavier elements K and Rb were predicted to adopt the sequence of I41/amdCmcadouble-hexagonal-close-packed. This sequence parallels the experimentally known structural sequence in Cs, which can be explained by the predominant d character of the valence electrons in K, Rb, and Cs at high-pressures. The major p character at the Fermi level in Li makes it distinct from K, Rb, and Cs.

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  • Received 18 February 2008

DOI:https://doi.org/10.1103/PhysRevB.78.014102

©2008 American Physical Society

Authors & Affiliations

Yanming Ma1,2, Artem R. Oganov1,3, and Yu Xie2

  • 1Laboratory of Crystallography, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland
  • 2National Laboratory of Superhard Materials, Jilin University, Changchun 130012, People’s Republic of China
  • 3Geology Department, Moscow State University, 119899 Moscow, Russia

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Vol. 78, Iss. 1 — 1 July 2008

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