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First-Principles Structural Optimization of Cubic Approximant Cd6Ca

Published online by Cambridge University Press:  01 February 2011

Kazuki Nozawa  and
Yasushi Ishii
Kazuki Nozawa
Affiliation:
SORST, Japan Science and Technology Agency (SORST-JST) Kawaguchi, Saitama 332–0012, Japan Depertment of Physics, Chuo University Kasuga, Tokyo 112–8551, Japan
Yasushi Ishii
Affiliation:
SORST, Japan Science and Technology Agency (SORST-JST) Kawaguchi, Saitama 332–0012, Japan Depertment of Physics, Chuo University Kasuga, Tokyo 112–8551, Japan
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Abstract

First-principles structural optimization is carried out for cubic Cd6Ca crystal with 168 atoms in a unit cell. The unit cell of Cd6Ca involves two four-layered icosahedral atomic clusters and 36 glue Cd atoms. Calculations are performed to determine energy cost owing to different orientations of the Cd tetrahedron, which is the innermost shell of the icosahedral cluster. Energetically favorable ordering of central Cd tetrahedra is such that the nearest neighboring tetrahedra is oriented in an anti-parallel fashion. As a result of the structural optimization, significant changes of atomic positions are observed in the first and second shells. The optimal nearest neighbor interatomic distance between the first and second shells is found to be close to the nearest neighbor distance of pure Cd. It is found that the pseudogap in the total density of states is enhanced as a result of the structural relaxation.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 805: Symposium LL – Quasicrystals , 2003 , LL1.9
Copyright
Copyright © Materials Research Society 2004

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References

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