Thermodynamic uncertainty relations and molecular-scale energy conversion

Area of Science:

• Thermodynamics
• Statistical Mechanics
• Molecular Systems

Background:

• The thermodynamic uncertainty relation (TUR) is a key constraint for nonequilibrium steady states.
• It relates entropy production rate to current fluctuations, impacting molecular energy conversion efficiency.
• A multidimensional version (MTUR) has been proposed to potentially improve these bounds.

Purpose of the Study:

• To apply and compare the TUR and MTUR to molecular-scale energy conversion models.
• To evaluate their effectiveness as bounds for entropy generation and thermodynamic efficiency.
• To identify regimes where these relations are most applicable.

Main Methods:

• Modeling molecular energy conversion with multidimensional periodic potentials.
• Applying the thermodynamic uncertainty relation (TUR) and multidimensional thermodynamic uncertainty relation (MTUR).
• Analyzing entropy generation rates and thermodynamic efficiency bounds.

Main Results:

• Both TUR and MTUR provide universal lower bounds on entropy generation and upper bounds on efficiency.
• MTUR offers a significantly tighter constraint than TUR by incorporating correlations between degrees of freedom.
• MTUR provides tight bounds near and far from equilibrium, but not in intermediate regimes.

Conclusions:

• The MTUR is generally more suitable than the TUR for analyzing molecular energy conversion processes.
• Both TUR and MTUR show limitations, diverging from actual entropy generation in specific regimes.
• These findings highlight the importance of considering multidimensional correlations for accurate thermodynamic bounds.