skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Ab Initio Study of Polonium

Abstract

Polonium is the only element with a simple cubic (sc) crystal structure. Atoms in solid polonium sit at the corners of a simple cubic unit cell and no where else. Polonium has a valence electron configuration 6s{sup 2}6p{sup 4} (Z = 84). The low temperature {alpha}-phase transforms into the rhombohedral (trigonal) {beta} structure at {approx}348 K. The sc {alpha}-Po unit cell constant is a = 3.345 A. The beta form of polonium ({beta}-Po) has the lattice parameters, a{sub R} = 3.359 A and a rhombohedral angle 98 deg. 13'. We have performed an ab initio electronic structure calculation by using the density functional theory. We have performed the calculation with and without spin-orbit (SO) coupling by using both the LDA and the GGA for the exchange-correlations. The k-points in a simple cubic BZ are determined by R (0.5, 0.5, 0.5), {gamma} (0, 0, 0), X (0.5, 0, 0), M (0.5, 0.5, 0) and {gamma} (0, 0, 0). Other directions of k-points are {gamma} (0, 0, 0), X (0.5, 0, 0), R (0.5, 0.5, 0.5) and {gamma} (0, 0, 0). The SO splittings of p states at the {gamma} point in the GGA+SO scheme for {alpha}-Po are 0.04 eV and 0.02more » eV while for the {beta}-Po these are 0.03 eV and 0.97 eV. We have also calculated the vibrational spectra for the unit cells in both the structures. We find that exchanging of a Po atom by Pb atom produces several more bands and destabilizes the {beta} phase.« less

Authors:
; ;  [1]
  1. Department of Physics, University of Malaya Kuala Lumpur, 50603 (Malaysia)
Publication Date:
OSTI Identifier:
21143306
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1017; Journal Issue: 1; Conference: PERFIK 2007: National physics conference 2007 on current issues of physics in Malaysia, Kuala Terengganu (Malaysia), 26-28 Dec 2007; Other Information: DOI: 10.1063/1.2940638; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ATOMS; CORRELATIONS; CUBIC LATTICES; DENSITY FUNCTIONAL METHOD; ELECTRONIC STRUCTURE; ELECTRONS; L-S COUPLING; LATTICE PARAMETERS; P STATES; PHASE TRANSFORMATIONS; POLONIUM; SOLIDS; SPIN; VALENCE

Citation Formats

Zabidi, Noriza Ahmad, Kassim, Hasan Abu, and Shrivastava, Keshav N. Ab Initio Study of Polonium. United States: N. p., 2008. Web. doi:10.1063/1.2940638.
Zabidi, Noriza Ahmad, Kassim, Hasan Abu, & Shrivastava, Keshav N. Ab Initio Study of Polonium. United States. doi:10.1063/1.2940638.
Zabidi, Noriza Ahmad, Kassim, Hasan Abu, and Shrivastava, Keshav N. Tue . "Ab Initio Study of Polonium". United States. doi:10.1063/1.2940638.
@article{osti_21143306,
title = {Ab Initio Study of Polonium},
author = {Zabidi, Noriza Ahmad and Kassim, Hasan Abu and Shrivastava, Keshav N.},
abstractNote = {Polonium is the only element with a simple cubic (sc) crystal structure. Atoms in solid polonium sit at the corners of a simple cubic unit cell and no where else. Polonium has a valence electron configuration 6s{sup 2}6p{sup 4} (Z = 84). The low temperature {alpha}-phase transforms into the rhombohedral (trigonal) {beta} structure at {approx}348 K. The sc {alpha}-Po unit cell constant is a = 3.345 A. The beta form of polonium ({beta}-Po) has the lattice parameters, a{sub R} = 3.359 A and a rhombohedral angle 98 deg. 13'. We have performed an ab initio electronic structure calculation by using the density functional theory. We have performed the calculation with and without spin-orbit (SO) coupling by using both the LDA and the GGA for the exchange-correlations. The k-points in a simple cubic BZ are determined by R (0.5, 0.5, 0.5), {gamma} (0, 0, 0), X (0.5, 0, 0), M (0.5, 0.5, 0) and {gamma} (0, 0, 0). Other directions of k-points are {gamma} (0, 0, 0), X (0.5, 0, 0), R (0.5, 0.5, 0.5) and {gamma} (0, 0, 0). The SO splittings of p states at the {gamma} point in the GGA+SO scheme for {alpha}-Po are 0.04 eV and 0.02 eV while for the {beta}-Po these are 0.03 eV and 0.97 eV. We have also calculated the vibrational spectra for the unit cells in both the structures. We find that exchanging of a Po atom by Pb atom produces several more bands and destabilizes the {beta} phase.},
doi = {10.1063/1.2940638},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1017,
place = {United States},
year = {Tue May 20 00:00:00 EDT 2008},
month = {Tue May 20 00:00:00 EDT 2008}
}
  • The structural, electronic and elastic properties of AB type (A = Tc, B = Nb and Ta) technetium intermetallic compounds are studied using full potential linearized plane wave (FP-LAPW) method within generalized gradient approximation (GGA). The calculated lattice parameters agree well with the experimental results. The elastic constants obey the stability criteria for cubic system. Ductility for these compounds has been analyzed using the Pugh’s rule and Cauchy’s pressure and found that all the compounds are ductile in nature. Bonding nature is discussed in terms of Fermi surface and band structures.
  • Ga- and As-terminated GaAs(100) surfaces are studied through first-principles density-functional pseudopotential calculations of the energies of surfaces with different stoichiometries and reconstructions. We predict structural transitions as a function of Ga and As chemical potentials within an experimentally accessible range which is shown to be fixed by the bulk energies of Ga, As, and GaAs. The bulk energies are determined accurately by the ab initio calculations. The predicted surface stoichiometries are in good agreement with experimental data.
  • A new two-configuration self-consistent field (SCF) plus dispersion potential for the interaction of OH with H[sub 2] is presented. The ground state of OH is a [sup 2][Pi] state leading to a two component potential which is diagonal in the adiabatic electronic basis in which the quantum chemical calculations are done. The transformation between the adiabatic basis and the electronic basis used in collision calculations is described. The transformed potential matrix is Hermitian in this electronic basis when OH--H[sub 2] configurations with no plane of symmetry are considered. The orientation dependence of the elements of the potential matrix is givenmore » in the form of a spherical expansion and the results are compared with previous potential calculations. The comparison is discussed in terms of the dependence on the orientation of the H[sub 2] molecule.« less
  • The optimized geometry, harmonic vibrational frequencies, and infrared absorption intensities of the lithium trifluoromethanesulfonate (triflate) ion pair, CF[sub 3]SO[sub 3]-Li have been investigated using the ab initio self-consistent Hartree-Fock and correlated second-order Moller-Plesset perturbation theory with the 6-31G* and lower basis sets. In the optimized structure the lithium cation is bound to two of the oxygens of the SO[sub 3] group forming a bidentate complex with C[sub s] symmetry. A local minimum with a monodentate structure was obtained in the HF/3-21G* calculations. The energy difference between the mono- and bidentate structures of the complex is predicted to be nearly 39more » kJmol[sup [minus]1] in this basis. A splitting of 230 and 158 cm[sup [minus]1] is obtained for the antisymmetric SO[sub 3] stretching for the bi- and monodentate coordination of the lithium cation with the free anion, respectively. The infrared spectrum of lithium triflate in poly(propylene oxide) shows a splitting of 43 cm[sup [minus]1]. The strong interaction of the metal cation with the anion in the 1:1 complex thus overemphasizes the [open quotes]splitting behavior[close quotes] observed for lithium triflate dissolved in polymers. In the bidentate (MP2/6-31G*) complex the symmetric SO[sub 3] stretching shows a downshift of 38 cm[sup [minus]1], in contrast to an upshift of 47 cm[sup [minus]1] for the monodentate complex. 22 refs., 2 figs., 6 tabs.« less