Determination of the structural parameters of an incommensurate phase from first principles: the case of Sc-II

We propose a procedure to accurately describe the structural parameters of an incommensurate phase using ab initio methods by approximating it with a set of analogous commensurate supercells. We apply this approach to obtain the structural parameters of the Sc-II phase, which has recently been ident...

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Bibliographic Details
Published in:Physical review letters 2009-02, Vol.102 (8), p.085701-085701, Article 085701
Main Authors: Arapan, Sergiu, Skorodumova, Natalia V, Ahuja, Rajeev
Format: Article
Language:English
Subjects:
BARIUM-IV
CRYSTAL-STRUCTURE
Fysik
GENERALIZED GRADIENT APPROXIMATION
HIGH-PRESSURE PHASE
NATURAL SCIENCES
NATURVETENSKAP
Physics
SCANDIUM
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Summary:We propose a procedure to accurately describe the structural parameters of an incommensurate phase using ab initio methods by approximating it with a set of analogous commensurate supercells. We apply this approach to obtain the structural parameters of the Sc-II phase, which has recently been identified as a complex incommensurate structure similar to Sr-V. The calculated incommensurate ratio gamma, lattice parameters, and Wyckoff positions of Sc-II are in excellent agreement with the available experimental data. Our results show that gamma increases with pressure up to 60 GPa approaching but never reaching the commensurate value 4/3. Hence calculations do not confirm the prediction made based on the reanalyzing of experimental data. When pressure exceeds 70 GPa, gamma shows a sharp decrease that might be considered as the precursor of a new structural phase transition.
ISSN:0031-9007
1079-7114
1079-7114
DOI:10.1103/PhysRevLett.102.085701