Structural, mechanical, thermodynamic, and electronic properties of thorium hydrides from first-principles

We perform first-principles calculations of the structural, electronic, mechanical, and thermodynamic properties of thorium hydrides (ThH2 and Th4H15) based on the density functional theory with generalized gradient approximation. The equilibrium geometries, the total and partial densities of states, charge density, elastic constants, elastic moduli, Poisson's ratio, and phonon dispersion curves for these materials are systematically investigated and analyzed in comparison with experiments and previous calculations. These results show that our calculated equilibrium structural parameters are well consistent with experiments. The Th-H bonds in all thorium hydrides exhibit weak covalent character, but the ionic properties for ThH2 and Th4H15 are different due to their different hydrogen concentration. It is found that while in ThH2 about 1.5 electrons transfer from each Th atom to H, in Th4H15 the charge transfer from each Th atom is around 2.1 electrons. Our calculated phonon spectrum for the stable body-centered tetragonal phase of ThH2 accords well with experiments. In addition we show that ThH2 in the fluorite phase is mechanically and dynamically unstable.

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Made available in DSpace on 2010-07-18T13:55:36Z (GMT). No. of bitstreams: 1 Structural, mechanical, thermodynamic, and electronic properties of thorium hydrides from first-principles.pdf: 1156944 bytes, checksum: f4ec94b102aebde2cfacf3eecc82e836 (MD5) Previous issue date: 2010

This work was supported by the Foundations for Development of Science and Technology of China Academy of Engineering Physics under Grants No. 2009B0301037 and No. 2009A0102005 and NCET of the Ministry of Education of China (NCET-08-0883).

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This work was supported by the Foundations for Development of Science and Technology of China Academy of Engineering Physics under Grants No. 2009B0301037 and No. 2009A0102005 and NCET of the Ministry of Education of China (NCET-08-0883).