Low Temperature Physics: 37, 791 (2011); https://doi.org/10.1063/1.3665873 (7 pages)
Fizika Nizkikh Temperatur: Volume 37, Number 9-10 (September 2011), p. 992-1000    ( to contents , go back )

On chemical bonding and distribution of helium in hcp beryllium

A.S. Bakai

National Science Center "Kharkov Institute of Physics and Technology" 1 Academicheskaya St., Kharkov 61108, Ukraine

A.N. Timoshevskii, and B.Z. Yanchitsky

Institute of Magnetism, 36-b Vernadskogo Blvd., Kyiv 03142, Ukraine
E-mail: tim@imag.kiev.ua
pos Анотація:

Received March 28, 2011

Abstract

The electron density of states and electron charge distribution in the hcp Be – He system are investigated using first principle ab-initio calculations. It is found, that, contrary to predictions of the “jelly” model, that the most energetically favorable position of helium atom is located at the triangle face of two adjacent tetrahedra. At this position the electron density of beryllium atoms has a maximum value and there is a chemical bonding between helium and beryllium. The calculated binding energy of helium is approximately 5.6 eV. The hybridisation of electronic states and electronic charge distribution are investigated in details. The solution energy of He in hcp Be is calculated. Various interstitial positions of He and small helium-vacancy complexes in hcp Be are investigated. It is shown, that helium at substitution position favors formation of divancies.

PACS: 31.15A– Ab initio simulations;
PACS: 61.72.S– Impurities in crystals.

Key words: helium and vacancies in beryllium, electronic structure, ab-initio methods

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