Publication: Ab initio study of icosahedral Al-Pd-Mn quasicrystals: Structural model, electric field gradients, and negative valence of Mn
All || By Area || By Year| Title | Ab initio study of icosahedral Al-Pd-Mn quasicrystals: Structural model, electric field gradients, and negative valence of Mn | Authors/Editors* | E. S. Zijlstra, S.K. Bose, M. Klanjsek, P. Jeglic, and J. Dolinsek |
|---|---|
| Where published* | Phys. Rev. B |
| How published* | Journal |
| Year* | 2005 |
| Volume | 72 |
| Number | |
| Pages | 174206 |
| Publisher | Americal Physical Society |
| Keywords | |
| Link | http://0-link.aps.org.catalogue.library.brocku.ca:80/abstract/PRB/v72/e174206 |
| Abstract |
The atomic and electronic structures of the Quandt-Elser model of i-Al70.8Pd21.5Mn7.7 [A. Quandt and V. Elser, Phys. Rev. B 61, 9336 (2000)] are studied by pseudopotential and full-potential linear augmented plane-wave methods. A model with a lower total energy than the original Quandt-Elser model (DeltaE=â0.03 eV/atom) is obtained by moving one of the Al atoms on a cube in the Mackay void away from its high symmetry position and by performing a subsequent structural relaxation. The electronic density of states of this modified Quandt-Elser model is found to be similar to that of the model of Katz and Gratias, but with a more pronounced pseudogap near the Fermi energy. Good agreement is obtained with an available photoemission spectrum, but calculated electric field gradients do not reproduce the angular dependence of a 27Al nuclear magnetic resonance spectrum. By introducing vacancies at Mn sites and by comparing the filling of bands near the Fermi energy for the models with and without a vacancy, it is found that the Mn atoms have an apparent negative number of â3.2 valence electrons independent of the Mn site. It is argued that this apparent negative number of valence electrons is due to the filling of Mn-d states below the Fermi energy. |
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