Are light alkali metals still metals under high pressure

  title={Are light alkali metals still metals under high pressure},
  author={Fabio Siringo and Renato Pucci and Giuseppe G. N. Angilella},
  journal={High Pressure Research},
The extended Hubbard Hamiltonian on a bcc lattice is studied at half-filling and for a finite hopping between next-nearest neighbours, in mean-field approximation . An ionic insulating broken-symmetry phase is predicted for any hydrogenoid bcc solid in the density range \(1.0<r_s <2.6\). The occurrence of an ionic phase would explain the failure to achieve hydrogen metallization at high pressures . Moreover, a metal–insulator transition is expected for sodium in the 100 GPa region. 
Light alkali metals such as lithium have been predicted to undergo a metal-insulator transition at high pressure, the insulating phase being characterized by a considerable reduction of lattice
Pairing in dense lithium
The light alkali metals have played an important role in the developing understanding of the electronic structure of simple metals. These systems are commonly viewed in terms of an underlying
On structural studies of high-density potassium and sodium
The alkali elements at ambient conditions are well described by the nearly-free electron (NFE) model, yet show a remarkable departure from this “simple” behaviour with increasing pressure.
High pressure electrides: a predictive chemical and physical theory.
By using a He lattice model to compress (with minimal orbital interaction at moderate pressures between the surrounding He and the contained atoms or molecules) atoms and an interstitial space, this work is able to semiquantitatively explain and predict the propensity of various elements to form HPEs.
Observation of shell structure in sodium nanowires
The quantum states of a system of particles in a finite spatial domain in general consist of a set of discrete energy eigenvalues; these are usually grouped into bunches of degenerate or close-lying
Pressure-induced electronic topological transitions in low dimensional superconductorsEHPRG Award Le
The high-Tc cuprate superconductors are characterized by a quasi-two-dimensional layered structure where most of the physics relevant for high-Tc superconductivity is believed to take place. In such
The chemical imagination at work in very tight places.
This account discusses in detail an overlapping hierarchy of responses to increased density: a) squeezing out van der Waals space (for molecular crystals); b) increasing coordination; c) decreasing the length of covalent bonds and the size of anions; and d) in an extreme regime, moving electrons off atoms and generating new modes of correlation.
High-pressure electrides: From design to synthesis
Electrides are unique ionic compounds that electrons serve as the anions. Many electrides with fascinating physical and chemical properties have been discovered at ambient condition. Under pressure,
Pressure effects on band structures in dense lithium
We studied the change of the band structures in some structures of Li predicted at high pressures, using GGA and GW calculations. The width of the 1s band coming from the 1s electron of Li shows
Theoretical Descriptors of Electrides.
Eight common theoretical descriptors of electrides are surveyed for their efficacy in identifying these materials and density-based descriptors such as the electron localization function (ELF) and localized-orbital locator (LOL) are shown to be the most consistently reliable.


High-Pressure Structural Phase Transitions in Na, Mg, and Al
First-principles total-energy calculations by two independent methods predict new transition-metal-like sequences of stable crystal structures in the third-period simple metals Na, Mg, and Al, under
High-pressure dielectric catastrophe and the possibility that the hydrogen-A phase is metallic
Recently a new phase of solid molecular hydrogen called hydrogen-A was found to occur for pressures greater than 153 GPa (1.53 Mbar) at 77 K. In this paper, from measurements of the dispersion of the
Pairing instabilities in dense hydrogen.
  • Ashcroft
  • Materials Science, Medicine
    Physical review. B, Condensed matter
  • 1990
It can be shown that the intramolecular potential suffers very significant weakening at high compression, this trend being fully understandable by application of the rigorous cusp condition, which constrains the electron density at the protons.
Extended infrared studies of high pressure hydrogen.
A new lattice mode is found which may be important for determining the structure of the high pressure A phase of parahydrogen and no evidence for the earlier reported Drude behavior is found within the range of study.
On the Possibility of a Metallic Modification of Hydrogen
Any lattice in which the hydrogen atoms would be translationally identical (Bravais lattice) would have metallic properties. In the present paper the energy of a body‐centered lattice of hydrogen is
Dense hydrogen: the reluctant alkali
In 1935 Eugene Wigner and his student Hillard Huntington predicted the existence of metallic hydrogen. Their calculations showed that, at high enough pressures, this dissociated form of hydrogen
Pressure-induced molecular dissociation in iodine at low temperatures
Abstract Synchrotron x-ray diffraction experiments at low temperatures have revealed that even at 35K the molecular dissociation starts taking place at PS=21.5 and finishes at Pf=26.1GPa. An
Lithium, Compression and High-Pressure Structure
Lithium is found to transform from a body-centered cubic (bcc) to a face-centered cubic (fcc) structure at 6.9 gigapascals (69 kilobars) and 296 kelvin. The relative volume of the bcc structured
Phase transitions in K and Rb under pressure
Abstract The crystal structures of K and Rb are studied by energy-dispersive X-ray diffraction at room temperature and pressures up to 35 GPa. Phase transitions occur in K at 11 GPa and around 20
Infrared Properties of Ortho and Mixed Crystals of Solid Deuterium at Megabar Pressures and the Question of Metallization in the Hydrogens.
  • Cui, Chen, Silvera
  • Materials Science, Medicine
    Physical review letters
  • 1995
The infrared absorption spectra of mixed ortho-para and pure ortho deuterium crystals down to liquid helium temperatures and pressures to 194 GPa are studied in search of an insulator-metal transition, finding no clear evidence of metallization.