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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Interactions leading to disordered ground states and unusual low-temperature behavior
Robert D Batten1, Frank H Stillinger, Salvatore Torquato
1Department of Chemical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 13, 2009
Summary
This study reveals anomalous low-temperature behavior in 2D systems with a specific k-space overlap potential. Ground states exhibit continuous energy degeneracy and vanishing shear elastic constants, leading to negative thermal expansion.
Area of Science:
- Condensed Matter Physics
- Statistical Mechanics
- Materials Science
Background:
- Previous work established that positive Fourier transforms of pair potentials with compact support yield disordered ground states.
- A constraint parameter (chi) allows tuning ground states from disordered to crystalline.
Purpose of the Study:
- Investigate the low-temperature behavior of 2D systems using a k-space overlap potential.
- Explore the relationship between energy landscape topography and system properties.
- Characterize ground states and their response to thermal and mechanical stimuli.
Main Methods:
- Utilized a k-space overlap potential defined by the intersection area of disks.
- Analyzed ground states at zero temperature (T=0).
- Employed molecular-dynamics simulations to study low-temperature behavior.
Main Results:
- Observed anomalous low-temperature behavior attributed to energy landscape topography.
- Found continuous energy degeneracy among Bravais-lattice configurations at T=0.
- Demonstrated vanishing shear elastic constants in ground-state Bravais lattices.
- Identified a significant fraction of normal modes with vanishing frequencies in both amorphous and crystalline ground states.
- Observed negative thermal expansion at low temperatures, with systems exhibiting a density maximum upon heating.
- Found that isothermal compression reduces local structure across all temperatures.
Conclusions:
- The k-space overlap potential leads to unique low-temperature phenomena in 2D systems.
- Ground states possess inherent instabilities, evidenced by vanishing elastic constants and normal mode frequencies.
- The system exhibits unusual responses to temperature and pressure, deviating from typical single-component systems.
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