title: Quasimolecules in Compressed Lithium.
abstract: Under high pressure, some materials form electrides, with valence electrons separated from all atoms and occupying interstitial regions. This is often accompanied by semiconducting or insulating behavior. The interstitial quasiatoms (ISQ) that characterize some high pressure electrides have been postulated to show some of the chemical features of atoms, including the potential of forming covalent bonds. It is argued that in the observed high-pressure semiconducting Li phase (oC40, Aba2), an example of such quasimolecules is realized. The theoretical evaluation of electron density, electron localization function, Wannier orbitals, and bond indices forms the evidence for covalently bonded ISQ pairs in this material. The quasimolecule concept thus provides a simple chemical perspective on the unusual insulating behavior of such materials, complementing the physical picture previously presented where the global crystal symmetry of the system plays the major role.
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Northridge, CA, 91330, USA.|Beijing Computational Science Research Center, Beijing 1, 0084, P.R. China.
authors.forename: Mao-Sheng
authors.initials: MS
authors.lastname: Miao
authors.affiliation: Department of Chemistry & Chemical Biology, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Roald
authors.initials: R
authors.lastname: Hoffmann
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Northridge, CA, 91330, USA.|Beijing Computational Science Research Center, Beijing 1, 0084, P.R. China.
authors.forename: Jorge
authors.identifier: 0000-0002-5406-3096
authors.initials: J
authors.lastname: Botana
authors.affiliation: Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC, USA.
authors.forename: Ivan I
authors.initials: II
authors.lastname: Naumov
authors.affiliation: Department of Civil and Environmental Engineering, The George Washington University, Washington, DC, 20052, USA.|Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA.
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Hemley
keywords: density functional calculations; high pressure electrides; interstitial quasi-atoms; maximally localized Wannier functions; semiconducting lithium