Nonequilibrium molecular energy transport across an oscillating temperature gradient

The dynamic modulation of temperature gradients offers a unique opportunity to manipulate the heat transport properties of nanoscale systems. Such oscillating thermal gradients can induce intriguing phenomena, including the transient hysteresis effects and the controllable storage of energy, which are absent in systems with static temperatures. In this study, we explore the impact of oscillating temperature gradients on heat transport properties within a molecular lattice. Our investigation employs analytical analysis and molecular dynamics simulations to examine vibrational heat flow in a model molecular lattice system, comprising a chain of interconnected particles bridging two heat baths with time-dependent temperatures. The derived heat current expressions in this system utilize both a stochastic energetics framework and a nonequilibrium Green's function approach, which are further verified by molecular dynamics simulations. Our theoretical framework provides insights into how temperature oscillations influence vibrational heat transmission across the lattice, unveiling a wealth of physics related to time-dependent, modulated thermal transport along molecular chains. These findings hold promise for advancing the understanding of non-steady-state intrinsic nonequilibrium regimes, both for slow quasistatic and fast-driven limits, and are particularly beneficial for the design of nanoscale heat transfer and phononics devices.