Ab initio calculations of MgF₂ (0 0 1) and (0 1 1) surface structure

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• 作者：A.F. Vassilyeva ; R.I. Eglitis ; E.A. Kotomin ; A.K. Dauletbekova
• 关键词：MgF₂ crystal ; Ab initio calculations ; Surfaces ; Atomic and electronic structure ; Surface relaxation ; Effective charges ; Optical band gap
• 刊名：Physica B
• 出版年：2010
• 出版时间：15 April 2010
• 年：2010
• 卷：405
• 期：8
• 页码：2125-2127
• 全文大小：151 K

文摘

We present the results of calculations of surface relaxations, rumplings, and charge distribution for the MgF₂ (0 0 1) and (0 1 1) surfaces using ab initio code Crystal-2003 and the hybrid exchange-correlation B3PW functional. These two neutral and polar surfaces show very small relaxation and negligible increase of covalent contribution to the chemical bonding thus remaining considerably ionic. The calculated bulk optical band gap is in a good agreement with the experimental value, whereas optical band gap for the polar (0 1 1) surface is reduced by 0.6 eV compared with the calculated bulk value, in contrast to the (0 0 1) surface gap which remains very close to the bulk.