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Structures and localized vibrational states of defects in graphite by tight-binding calculations
Rong Cheng1,2, Wen-Cai Lu1,2, K M Ho2
1College of Physics, Qingdao University, Qingdao, Shandong 266071, China.
Physical Chemistry Chemical Physics : PCCP
|September 7, 2022
Summary
Tight-binding calculations accurately model graphite's structure and defects. These simulations reveal localized vibrational modes in defective graphite, particularly strong for Frenkel pair, dual-vacancy, and dual-interstitial defects.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Computational Materials Science
Background:
- Graphite's unique electronic and structural properties are crucial for advanced materials.
- Understanding point defects is essential for predicting material behavior and performance.
- Accurate theoretical models are needed to simulate defect properties.
Purpose of the Study:
- To investigate the structural and vibrational properties of pristine and defected graphite.
- To evaluate the efficacy of a three-center tight-binding (TB) potential model.
- To analyze the localization of vibrational states induced by various point defects.
Main Methods:
- Utilized tight-binding (TB) calculations with a three-center TB potential model.
- Compared TB results with density-functional theory (DFT) calculations including van der Waals corrections.
- Analyzed atomic displacements associated with localized vibrational modes.
Main Results:
- The TB model accurately predicts graphite's inter-layer distance and defect structures without ad hoc corrections.
- TB results show good agreement with DFT calculations.
- Localized vibrational modes were observed in all defected graphite, with stronger localization for Frenkel pair, dual-vacancy, and dual-interstitial defects.
Conclusions:
- The three-center TB potential is a reliable and efficient tool for studying graphite and its point defects.
- Point defects significantly influence vibrational properties, leading to localized modes.
- Specific defect types exhibit pronounced localization, offering insights into their impact on material dynamics.
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