Superconductivity in lithium under high pressure investigated with density functional and Eliashberg theory

Yao, Yansun; Tse, John S.; Tanaka, K.; Marsiglio, F.; Ma, Yanming

doi:10.1103/physrevb.79.054524

Cited by 55 publications

(51 citation statements)

References 61 publications

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“…4e. Our results compare well with experimental measurements 46,47 and previous density functional calculations 48 . For example, T c is calculated to be 5.71 and 13.32 K for 20 and 30 GPa, respectively, compared with the values of 5.47 K for 20.3 and 30 GPa measured by Deemyad et al 46 .…”

Section: Articlesupporting

confidence: 91%

Pressure-stabilized lithium caesides with caesium anions beyond the −1 state

Botana

Miao

2014

Nat Commun

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Main group elements usually assume a typical oxidation state while forming compounds with other species. Group I elements are usually in the þ 1 state in inorganic materials. Our recent work reveals that pressure may make the inner shell 5p electrons of Cs reactive, causing Cs to expand beyond the þ 1 oxidation state. Here we predict that pressure can cause large electron transfer from light alkali metals such as Li to Cs, causing Cs to become anionic with a formal charge much beyond À 1. Although Li and Cs only form alloys at ambient conditions, we demonstrate that these metals form stable intermetallic Li n Cs (n ¼ 1-5) compounds under pressures higher than 100 GPa. Once formed, these compounds exhibit interesting structural features, including capped cuboids and dimerized icosahedra. Finally, we explore the possibility of superconductivity in metastable LiCs and discuss the effect of the unusual anionic state of Cs on the transition temperature.

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Section: Articlesupporting

confidence: 91%

Pressure-stabilized lithium caesides with caesium anions beyond the −1 state

Botana

Miao

2014

Nat Commun

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“…The Coulomb repulsion is taken into account in terms of the Coulomb pseudopotential, μÃ, scaled to a cutoff frequency (typically six times the maximum phonon frequency) (27). At 150 GPa, the predicted T c values were 235 K and 220 K using typical values for μÃ of 0.1 and 0.13, respectively.…”

Section: Resultsmentioning

confidence: 99%

Superconductive sodalite-like clathrate calcium hydride at high pressures

Wang

Tse

Tanaka

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

693

676

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Hydrogen-rich compounds hold promise as high-temperature superconductors under high pressures. Recent theoretical hydride structures on achieving high-pressure superconductivity are composed mainly of H 2 fragments. Through a systematic investigation of Ca hydrides with different hydrogen contents using particleswam optimization structural search, we show that in the stoichiometry CaH 6 a body-centered cubic structure with hydrogen that forms unusual "sodalite" cages containing enclathrated Ca stabilizes above pressure 150 GPa. The stability of this structure is derived from the acceptance by two H 2 of electrons donated by Ca forming an "H 4 " unit as the building block in the construction of the three-dimensional sodalite cage. This unique structure has a partial occupation of the degenerated orbitals at the zone center. The resultant dynamic Jahn-Teller effect helps to enhance electronphonon coupling and leads to superconductivity of CaH 6 . A superconducting critical temperature (T c ) of 220-235 K at 150 GPa obtained from the solution of the Eliashberg equations is the highest among all hydrides studied thus far.calcium hydride | sodalite structure

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“…If Uð eng Þ is fitted to a sinusoidal shape near the bcc structure, where eng ¼ 0, we get Li and Wang (1998) and Yashiro, Oho, and Tomita (2004) large strains; see, e.g., Krasko and Olson (1990), Jansen (1991), Herper, Hoffmann, andEntel (1999), Qiu and Marcus (1999), Qiu, Marcus, and Ma (2000a), Friák, Š ob, and Vitek (2001), Š ob et al (2002, Clatterbuck, Chrzan, and , 2003b, Tsetseris (2005), Liu et al (2008), Okatov et al (2009), and Leonov et al (2011. Other examples of works dealing with uniaxial loading are Zelený, Legut, and Š ob (2008) and Zelený and Šob (2008) on epitaxy, and Friák and Š ob (2008) and Djohari, Milstein, and Maroudas (2009) on bcc-hcp structures.…”

Section: B Homogeneous Deformation 1 Uniaxial Tensionmentioning

confidence: 99%

Lattice instabilities in metallic elements

et al. 2012

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Most metallic elements have a crystal structure that is either body-centered cubic (bcc), facecentered close packed, or hexagonal close packed. If the bcc lattice is the thermodynamically most stable structure, the close-packed structures usually are dynamically unstable, i.e., have elastic constants violating the Born stability conditions or, more generally, have phonons with imaginary frequencies. Conversely, the bcc lattice tends to be dynamically unstable if the equilibrium structure is close packed. This striking regularity essentially went unnoticed until ab initio total-energy calculations in the 1990s became accurate enough to model dynamical properties of solids in hypothetical lattice structures. After a review of stability criteria, thermodynamic functions in the vicinity of an instability, Bain paths, and how instabilities may arise or disappear when pressure, temperature, and/or chemical composition is varied are discussed. The role of dynamical instabilities in the ideal strength of solids and in metallurgical phase diagrams is then considered, and comments are made on amorphization, melting, and low-dimensional systems. The review concludes with extensive references to theoretical work on the stability properties of metallic elements.

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Superconductivity in lithium under high pressure investigated with density functional and Eliashberg theory

Cited by 55 publications

References 61 publications

Pressure-stabilized lithium caesides with caesium anions beyond the −1 state

Pressure-stabilized lithium caesides with caesium anions beyond the −1 state

Superconductive sodalite-like clathrate calcium hydride at high pressures

Lattice instabilities in metallic elements

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