Quantum bath augmented stochastic nonequilibrium atomistic simulations for molecular heat conduction

Area of Science:

• Computational physics
• Materials science
• Nanotechnology

Background:

• Classical molecular dynamics (MD) simulates heat conduction but lacks quantum effects at low temperatures.
• Quantum Landauer-type models omit crucial factors like anharmonicity and nonlinear responses.

Purpose of the Study:

• To develop an atomistic simulation method for molecular heat conduction that includes quantum effects.
• To create a model suitable for a wide temperature range, from low to high temperatures.

Main Methods:

• Incorporated quantum Bose-Einstein statistics into an "effective temperature" using a modified Langevin equation.
• Simulated anharmonic models using the Morse potential and compared them to harmonic interactions.
• Examined heat conduction in 1D polymer chains with quantum-augmented baths.

Main Results:

• The quasi-classical method shows significant deviations from classical MD at low temperatures, converging at high temperatures.
• The method accurately models substrate layout and molecular properties like anharmonicities and high-frequency modes.
• Chain length dependence of heat conduction was analyzed for polymer chains.

Conclusions:

• The developed quasi-classical effective temperature MD method accurately captures quantum effects in molecular heat conduction.
• This approach is versatile, applicable to various molecular systems and temperature ranges.
• The findings provide a more robust tool for understanding thermal transport at the nanoscale.