title: Prediction of Stable Ruthenium Silicides from First-Principles Calculations: Stoichiometries, Crystal Structures, and Physical Properties.
abstract: We present results of an unbiased structure search for stable ruthenium silicide compounds with various stoichiometries, using a recently developed technique that combines particle swarm optimization algorithms with first-principles calculations. Two experimentally observed structures of ruthenium silicides, RuSi (space group P2(1)3) and Ru2Si3 (space group Pbcn), are successfully reproduced under ambient pressure conditions. In addition, a stable RuSi2 compound with β-FeSi2 structure type (space group Cmca) was found. The calculations of the formation enthalpy, elastic constants, and phonon dispersions demonstrate the Cmca-RuSi2 compound is energetically, mechanically, and dynamically stable. The analysis of electronic band structures and densities of state reveals that the Cmca-RuSi2 phase is a semiconductor with a direct band gap of 0.480 eV and is stabilized by strong covalent bonding between Ru and neighboring Si atoms. On the basis of the Mulliken overlap population analysis, the Vickers hardness of the Cmca structure RuSi2 is estimated to be 28.0 GPa, indicating its ultra-incompressible nature.
authors.affiliation: Institute of Atomic and Molecular Physics, Sichuan University , Chengdu 610065, China.
authors.forename: Chuanzhao
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Institute of Atomic and Molecular Physics, Sichuan University , Chengdu 610065, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Kuang
authors.affiliation: Institute of Atomic and Molecular Physics, Sichuan University , Chengdu 610065, China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Jin
authors.affiliation: Department of Physics, Nanyang Normal University , Nanyang 473061, China.|Beijing Computational Science Research Center , Beijing 100084, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Lu
authors.affiliation: Department of Physics, Nanyang Normal University , Nanyang 473061, China.
authors.forename: Dawei
authors.initials: D
authors.lastname: Zhou
authors.affiliation: College of Physics and Electronic Information, Inner Mongolia University for the Nationalities , Tongliao 028043, China.
authors.forename: Peifang
authors.initials: P
authors.lastname: Li
authors.affiliation: College of Physics and Electronic Information, Inner Mongolia University for the Nationalities , Tongliao 028043, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Bao
authors.affiliation: Centre for Science at Extreme Conditions and SUPA, School of Physics and Astronomy, The University of Edinburgh , Edinburgh EH9 3JZ, United Kingdom.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hermann
keywords: crystal structures; electronic structures; hardness; mechanical properties; ruthenium silicides; stoichiometries