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Extended defects in a hard disk system and melting criteria
M V Kondrin1, Y B Lebed2, V V Brazhkin1
1Institute for High Pressure Physics RAS, Troitsk, 108840, Moscow, Russia. mkondrin@hppi.troitsk.ru.
Physical Chemistry Chemical Physics : PCCP
|April 7, 2026
Summary
The hard disk model
Area of Science:
- Physics
- Materials Science
Background:
- The hard sphere model is a fundamental approximation for fluids and solids.
- Few analytical results exist for 2D and 3D hard disk systems.
Purpose of the Study:
- Investigate the melting of the 2D hard disk system.
- Formulate melting criteria based on defect accumulation and jamming.
Main Methods:
- Analysis of extended defects in the crystalline phase.
- Examination of disk packing jamming.
- Application of Berezinskii-Kosterlitz-Thouless-Halperin-Nelson-Young theory.
Main Results:
- Melting criteria established: 25/21 ≤ Vm/V0 ≤ 5/4.
- 2D crystal melts into an anisotropic liquid.
- Second transition to isotropic liquid occurs at 5/4 ≤ Vi/V0 ≤ 13/9.
Conclusions:
- The study provides analytical insights into 2D hard disk system melting.
- Results align with established theories on phase transitions.
- Defect accumulation and jamming are key to understanding melting.
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