title: High pressure-induced distortion in face-centered cubic phase of thallium.
abstract: The complex and unusual high-pressure phase transition of III-A (i.e. Al, Ga, and In) metals have been investigated in the last several decades because of their interesting periodic table position between the elements having metallic and covalent bonding. Our present first principles-based electronic structure calculations and experimental investigation have revealed the unusual distortion in face-centered cubic (f.c.c.) phase of the heavy element thallium (Tl) induced by the high pressure. We have predicted body-centered tetragonal (b.c.t) phase at 83 GPa using an evolutionary algorithm coupled with ab initio calculations, and this prediction has been confirmed with a slightly distorted parameter ([Formula: see text] × a - c)/c lowered by 1% using an angle-dispersive X-ray diffraction technique. The density functional theory (DFT)-based calculations suggest that s-p mixing states and the valence-core overlapping of 6s and 5d states play the most important roles for the phase transitions along the pathway h.c.p[Formula: see text]f.c.c.[Formula: see text]b.c.t.
authors.affiliation: Department of Physics, Mahidol Wittayanusorn School, Nakhon Pathom 73170, Thailand; Thailand Center of Excellence in Physics, Commission on Higher Education, Bangkok 10400, Thailand.
authors.forename: Komsilp
authors.initials: K
authors.lastname: Kotmool
authors.affiliation: High Pressure Synergetic Consortium, Carnegie Institution of Washington, Argonne, IL 60439; Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China; Center for the Study of Matter at Extreme Conditions, Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33199.
authors.forename: Bing
authors.initials: B
authors.lastname: Li
authors.affiliation: Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, S-75120 Uppsala, Sweden.
authors.forename: Sudip
authors.initials: S
authors.lastname: Chakraborty
authors.affiliation: Thailand Center of Excellence in Physics, Commission on Higher Education, Bangkok 10400, Thailand; Extreme Conditions Physics Research Laboratory, Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Thiti
authors.initials: T
authors.lastname: Bovornratanaraks
authors.affiliation: Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, S-75120 Uppsala, Sweden.
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.affiliation: High Pressure Synergetic Consortium, Carnegie Institution of Washington, Argonne, IL 60439; Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China; Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015; mao@gl.ciw.edu rajeev.ahuja@physics.uu.se.
authors.forename: Ho-Kwang
authors.initials: HK
authors.lastname: Mao
authors.affiliation: Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, S-75120 Uppsala, Sweden; Applied Materials Physics, Department of Materials and Engineering, Royal Institute of Technology, S-100 44 Stockholm, Sweden mao@gl.ciw.edu rajeev.ahuja@physics.uu.se.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Ahuja
keywords: distorted face-centered cubic; first principle study; high pressure; phase transition; thallium