Excitonic Effects in Oxyhalide Scintillating Host Compounds

G, Swetha and V, Kanchana and M C, Valsakumar (2014) Excitonic Effects in Oxyhalide Scintillating Host Compounds. Journal of Applied Physics, 116 (13). pp. 1-10. ISSN 0021-8979

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Ab-initio calculations based on density functional theory have been performed to study the electronic, optical, mechanical, and vibrational properties of scintillator host compounds YOX (X=F, Cl, Br, and I). Semiempirical dispersion correction schemes are used to find the effect of van der Waals forces on these layered compounds and we found this effect to be negligible except for YOBr. Calculations of phonons and elastic constants showed that all the compounds studied here are both dynamically and mechanically stable. YOF and YOI are found to be indirect band gap insulators while YOCl and YOBr are direct band gap insulators. The band gap is found to decrease as we move from fluorine to iodine, while the calculated refractive index shows the opposite trend. As the band gap decreases on going down the periodic table from YOF to YOI, the luminescence increases. The excitonic binding energy calculated, within the effective mass approximation, is found to be more for YOF than the remaining compounds, suggesting that the excitonic effect to be more in YOF than the other compounds. The optical properties are calculated within the Time-Dependent Density Functional Theory (TDDFT) and compared with results obtained within the random phase approximation. The TDDFT calculations, using the newly developed bootstrap exchange-correlation kernel, showed significant excitonic effects in all the compounds studied here.

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IITH Creators:
IITH CreatorsORCiD
Item Type: Article
Uncontrolled Keywords: Excitonic effect
Subjects: Physics
Divisions: Department of Physics
Depositing User: Library Staff
Date Deposited: 17 Apr 2015 10:57
Last Modified: 14 Aug 2017 09:52
URI: http://raiith.iith.ac.in/id/eprint/1453
Publisher URL: https://dx.doi.org/10.1063/1.4896831
OA policy: http://www.sherpa.ac.uk/romeo/issn/0021-8979/
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