title: Electronic dynamics and plasmons of sodium under compression.
abstract: Sodium, which has long been regarded as one of the simplest metals, displays a great deal of structural, optical, and electronic complexities under compression. We compressed pure Na in the body-centered cubic structure to 52 GPa and in the face-centered cubic structure from 64 to 97 GPa, and studied the plasmon excitations of both structures using the momentum-dependent inelastic X-ray scattering technique. The plasmon dispersion curves as a function of pressure were extrapolated to zero momentum with a quadratic approximation. As predicted by the simple free-electron model, the square of the zero-momentum plasmon energy increases linearly with densification of the body-centered cubic Na up to 1.5-fold. At further compressions and in face-centered cubic Na above 64 GPa, the linear relation curves progressively toward the density axis up to 3.7-fold densification at 97 GPa. Ab initio calculations indicate that the deviation is an expected behavior of Na remaining a simple metal.
authors.affiliation: High Pressure Synergetic Consortium, and High Pressure Collaborative Access Team, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, IL 60439, USA. mao@gl.ciw.edu
authors.forename: Ho-Kwang
authors.initials: HK
authors.lastname: Mao
authors.forename: Yang
authors.initials: Y
authors.lastname: Ding
authors.forename: Yuming
authors.initials: Y
authors.lastname: Xiao
authors.forename: Paul
authors.initials: P
authors.lastname: Chow
authors.forename: Jinfu
authors.initials: J
authors.lastname: Shu
authors.forename: Sébastien
authors.initials: S
authors.lastname: Lebègue
authors.forename: Amy
authors.initials: A
authors.lastname: Lazicki
authors.forename: Rajeev
authors.initials: R
authors.lastname: Ahuja
mesh_terms: D004563:Electrochemistry / Q000379:methods; D004581:Electronics; D004583:Electrons; D005740:Gases; D008670:Metals / Q000737:chemistry; D008968:Molecular Conformation; D011312:Pressure; D012542:Scattering, Radiation; D012964:Sodium / Q000737:chemistry*; D014965:X-Rays
chemical_list: D005740:Gases; D008670:Metals; D012964:Sodium