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Self-sustained Molecular Rectification without External Driving or Information

Jiantang Jiang

Abstract

Rectifying thermal white noise into directed motion is generally believed to require the consumption of energy or information, as exemplified by Maxwell's demon-type feedback controllers. Here we demonstrate a molecular rectification mechanism that operates without any external energy or information flow. An ion-induced asymmetry between two liquid-vapor interfaces creates unequal surface barriers, enabling the harvesting and redistribution of surface energy released during condensation. Molecular dynamics simulations show that this intrinsic kinetic asymmetry sustains a persistent net water flux. Our results suggest that asymmetric potential energy landscape alone can rectify thermal fluctuations, revising the conventional understanding of noise-driven transport.

Self-sustained Molecular Rectification without External Driving or Information

Abstract

Rectifying thermal white noise into directed motion is generally believed to require the consumption of energy or information, as exemplified by Maxwell's demon-type feedback controllers. Here we demonstrate a molecular rectification mechanism that operates without any external energy or information flow. An ion-induced asymmetry between two liquid-vapor interfaces creates unequal surface barriers, enabling the harvesting and redistribution of surface energy released during condensation. Molecular dynamics simulations show that this intrinsic kinetic asymmetry sustains a persistent net water flux. Our results suggest that asymmetric potential energy landscape alone can rectify thermal fluctuations, revising the conventional understanding of noise-driven transport.
Paper Structure (5 sections, 11 equations, 3 figures)

This paper contains 5 sections, 11 equations, 3 figures.

Table of Contents

  1. Introduction
  2. Model and methods
  3. Intrinsic kinetic asymmetry
  4. Quantifying the Asymmetry via Relative Entropy
  5. Conclusion

Figures (3)

  • Figure 1: Simulation setup. HPM, hydrophobic porous membrane; FC, fixed charges on the pore sidewall; FI, free ions in water. The upper-left inset shows the top view of the HPM. The figure is not drawn to scale.
  • Figure 2: Variation of NNWM values as a function of time in simulations of PW and B1.
  • Figure 3: Liquid molecules trapped in a potential well composed of surface barriers A and B. PBH denotes the potential barrier height. The zero of potential energy is defined at the well bottom.