Speaker
Description
The Green-Kubo theory of atomic heat transport relies on the ambiguous decomposition of total energy into energies of individual atoms. The key challenge is to understand how thermodynamic properties such as heat conductivity can emerge from inherently ill-defined atomic energies. Here, we show that such ambiguity can be exploited as a guide to construct a general theory of heat transport by requiring the theory to take the same invariant form for all possible choices of atomic energies. By defining atomic gauges and associated transformations of atomic energies, we show that the gauge symmetry dictates the gauge-invariant form of macroscopic energy transfer, which is identified as heat. Consequently, arbitrary choices (even random shuffling) of atomic energies lead to the same heat conductivity 𝜅. The gauge theory also offers a novel variational method for calculating 𝜅, as demonstrated using machine learning-inferred atomic energies of $Cu_{2}S$, an intriguing solid-liquid hybrid thermoelectric material.
