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Title: Ultra-sensitive pressure dependence of bandgap of rutile-GeO{sub 2} revealed by many body perturbation theory

The reported values of bandgap of rutile GeO{sub 2} calculated by the standard density functional theory within local-density approximation (LDA)/generalized gradient approximation (GGA) show a wide variation (∼2 eV), whose origin remains unresolved. Here, we investigate the reasons for this variation by studying the electronic structure of rutile-GeO{sub 2} using many-body perturbation theory within the GW framework. The bandgap as well as valence bandwidth at Γ-point of rutile phase shows a strong dependence on volume change, which is independent of bandgap underestimation problem of LDA/GGA. This strong dependence originates from a change in hybridization among O-p and Ge-(s and p) orbitals. Furthermore, the parabolic nature of first conduction band along X-Γ-M direction changes towards a linear dispersion with volume expansion.
Authors:
;  [1] ;  [2]
  1. Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India)
  2. Department of Physics, Indian Institute of Science, Bangalore 560012 (India)
Publication Date:
OSTI Identifier:
22493516
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 6; Other Information: (c) 2015 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; APPROXIMATIONS; DENSITY; DENSITY FUNCTIONAL METHOD; ELECTRONIC STRUCTURE; ENERGY GAP; EV RANGE; GERMANIUM OXIDES; MANY-BODY PROBLEM; PERTURBATION THEORY; PRESSURE DEPENDENCE; RUTILE; VALENCE; VARIATIONS