title: Mercury under Pressure acts as a Transition Metal: Calculated from First Principles.
abstract: The inclusion of Hg among the transition metals is readily debated. Recently, molecular HgF4 was synthesized in a low-temperature noble gas but the potential of Hg to form compounds beyond a +2 oxidation state in a stable solid remains unresolved. We propose high-pressure techniques to prepare unusual oxidation states of Hg-based compounds. Using an advanced structure search algorithm and first-principles electronic structure calculations, we find that under high pressure Hg in Hg-F compounds transfers charge from the d orbitals to the F, thus behaving as a transition metal. Oxidizing Hg to +4 and +3 yielded the thermodynamically stable compounds HgF4 and HgF3. The former consists of HgF4 planar molecules, a typical geometry for d(8) metal centers. HgF3 is metallic and ferromagnetic owing to the d(9) configuration of Hg, with a large gap between its partially occupied and unoccupied bands under high pressure.
authors.affiliation: Beijing Computational Science Research Center, Beijing 100094 (P.R. China).
authors.forename: Jorge
authors.initials: J
authors.lastname: Botana
authors.affiliation: Beijing Computational Science Research Center, Beijing 100094 (P.R. China).|Institute of Condensed Matter Physics, Linyi University, Linyi 276005 (P.R. China).
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Wang
authors.affiliation: Beijing Computational Science Research Center, Beijing 100094 (P.R. China).|School of Science, JiangXi University of Science and Technology, Ganzhou 341000 (P.R. China).
authors.forename: Chunju
authors.initials: C
authors.lastname: Hou
authors.affiliation: Department of Physics, Beijing Normal University, Beijing 100875 (P.R. China).
authors.forename: Dadong
authors.initials: D
authors.lastname: Yan
authors.affiliation: Beijing Computational Science Research Center, Beijing 100094 (P.R. China).
authors.forename: Haiqing
authors.initials: H
authors.lastname: Lin
authors.affiliation: Beijing Computational Science Research Center, Beijing 100094 (P.R. China).|State Key Lab of Superhard Materials, Jilin University, Changchun 130012 (P.R. China).
authors.forename: Yanming
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Beijing Computational Science Research Center, Beijing 100094 (P.R. China). mmiao@csun.edu.|Department of Chemistry and Biochemistry, California State University, Northridge, CA 91330 (USA). mmiao@csun.edu.|Materials Department and Materials Research Laboratory, University of California, Santa Barbara, CA 93106-5050 (USA). mmiao@csun.edu.
authors.forename: Mao-sheng
authors.initials: MS
authors.lastname: Miao
keywords: ab initio calculations; crystal structure search; high oxidation state; high-pressure chemistry; mercury