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Title: Structural, electronic, vibrational, and dielectric properties of LaBGeO{sub 5} from first principles

Structural, electronic, vibrational, and dielectric properties of LaBGeO{sub 5} with the stillwellite structure are determined based on ab initio density functional theory. The theoretically relaxed structure is found to agree well with the existing experimental data with a deviation of less than 0.2%. Both the density of states and the electronic band structure are calculated, showing five distinct groups of valence bands. Furthermore, the Born effective charge, the dielectric permittivity tensors, and the vibrational frequencies at the center of the Brillouin zone are all obtained. Compared to existing model calculations, the vibrational frequencies are found in much better agreement with the published experimental infrared and Raman data, with absolute and relative rms values of 6.04 cm{sup −1}, and 1.81%, respectively. Consequently, numerical values for both the parallel and perpendicular components of the permittivity tensor are established as 3.55 and 3.71 (10.34 and 12.28), respectively, for the high-(low-)frequency limit.
Authors:
; ; ;  [1] ; ;  [2] ;  [3]
  1. Department of Physics, The University of Jordan, 11942 Amman (Jordan)
  2. Institute of Condensed Matter and Nanosciences (IMCN/NAPS), Université Catholique de Louvain (UCL), 8 Chemin des étoiles, B-1348 Louvain-la Neuve (Belgium)
  3. (ETSF) (Belgium)
Publication Date:
OSTI Identifier:
22278031
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 7; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BRILLOUIN ZONES; COMPARATIVE EVALUATIONS; DENSITY FUNCTIONAL METHOD; DIELECTRIC MATERIALS; EFFECTIVE CHARGE; ELECTRONIC STRUCTURE; PERMITTIVITY; RAMAN SPECTRA; TENSORS; VALENCE