Crystal structure of the pressure-induced metallic phase of SiH4 from ab initio theory
2008 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 105, no 43, 16454-16459 p.Article in journal (Refereed) Published
Metallization of pure solid hydrogen is of great interest, not least because it could lead to high-temperature superconductivity, but it continues to be an elusive goal because of great experimental challenges. Hydrogen-rich materials, in particular, CH4, SiH4, and GeH4, provide an opportunity to study related phenomena at experimentally achievable pressures, and they too are expected to be high-temperature superconductors. Recently, the emergence of a metallic phase has been observed in silane for pressures just above 60 GPa. However, some uncertainty exists about the crystal structure of the discovered metallic phase. Here, we show by way of elimination, that a single structure that possesses all of the required characteristics of the experimentally observed metallic phase of silane from a pool of plausible candidates can be identified. Our density functional theory and GW calculations show that a structure with space group P4/nbm is metallic at pressures > 60 GPa. Based on phonon calculations, we furthermore demonstrate that the P4/nbm structure is dynamically stable at > 43 GPa and becomes the ground state at 97 GPa when zero-point energy contributions are considered. These findings could lead the way for further theoretical analysis of metallic phases of hydrogen-rich materials and stimulate experimental studies.
Place, publisher, year, edition, pages
2008. Vol. 105, no 43, 16454-16459 p.
hydrogen-rich, metallization, generalized gradient approximation, hydrogen, exchange, superconductivity, equation, silane, state
IdentifiersURN: urn:nbn:se:kth:diva-17975DOI: 10.1073/pnas.0804148105ISI: 000260913500012ScopusID: 2-s2.0-55949134174OAI: oai:DiVA.org:kth-17975DiVA: diva2:336020
QC 201005252010-08-052010-08-05Bibliographically approved