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Published on: August 22, 2017
Mechanical properties of solid C(60) studied with density functional tight binding method augmented by an empirical
Chao Feng1, Chong Zhang, Ruiqin Zhang
1Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR, People's Republic of China. Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, People's Republic of China.
Summary
This study calculates the bulk modulus of solid carbon 60 (C60) using density functional theory. Results show good agreement with experiments, highlighting the importance of van der Waals forces for understanding C60 solids.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Computational Chemistry
Background:
- Fullerene C60 is a significant allotrope of carbon with unique electronic and structural properties.
- Understanding the mechanical behavior of solid C60 under compression is crucial for its applications.
- Previous studies have explored C60 properties, but precise modeling of its response to pressure requires advanced computational methods.
Purpose of the Study:
- To calculate the bulk modulus of solid face-centered cubic (fcc) C60.
- To investigate the structural and electronic changes in C60 molecules under compression.
- To assess the role of van der Waals forces in accurately describing solid C60.
Main Methods:
- Density Functional Tight Binding (DFTB) method was employed for calculations.
- Empirical van der Waals (vdW) forces were incorporated to account for weak intermolecular interactions.
- Calculations focused on the solid fcc phase of C60.
Main Results:
- The calculated bulk modulus is 9.1 GPa, showing good agreement with experimental data.
- Significant changes in the geometric structure and carbon atom hybridization of C60 were observed under compression.
- A reduction in the Highest Occupied Molecular Orbital-Lowest Unoccupied Molecular Orbital (HOMO-LUMO) gap was found due to π-orbital overlap.
Conclusions:
- The DFTB method, augmented with vdW corrections, accurately predicts the bulk modulus of solid fcc C60.
- Compression induces substantial structural modifications and electronic band gap narrowing in solid C60.
- Dispersion energy corrections are essential for a quantitative description of weakly bound C60 solids.
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