Importance of Unit Cells in Accurate Evaluation of the Characteristics of Graphene
| Autor: | Hassan Sabzyan, Narges Sadeghpour |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Materials science
Graphene Phonon General Physics and Astronomy Nanotechnology 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences law.invention law 0103 physical sciences Density functional theory Physical and Theoretical Chemistry 010306 general physics 0210 nano-technology Unit (ring theory) Mathematical Physics |
| Zdroj: | Zeitschrift für Naturforschung A. 71:315-320 |
| ISSN: | 1865-7109 0932-0784 |
| DOI: | 10.1515/zna-2015-0444 |
| Popis: | Effects of the size of the unit cell on energy, atomic charges, and phonon frequencies of graphene at the Γ point of the Brillouin zone are studied in the absence and presence of an electric field using density functional theory (DFT) methods (LDA and DFT-PBE functionals with Goedecker–Teter–Hutter (GTH) and Troullier–Martins (TM) norm-conserving pseudopotentials). Two types of unit cells containing nC=4–28 carbon atoms are considered. Results show that stability of graphene increases with increasing size of the unit cell. Energy, atomic charges, and phonon frequencies all converge above nC=24 for all functional-pseudopotentials used. Except for the LDA-GTH calculations, application of an electric field of 0.4 and 0.9 V/nm strengths does not change the trends with the size of the unit cell but instead slightly decreases the binding energy of graphene. Results of this study show that the choice of unit cell size and type is critical for calculation of reliable characteristics of graphene. |
| Databáze: | OpenAIRE |
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