Transport phenomena at a critical point: Thermal conduction in the Creutz cellular automaton

The nature of energy transport around a critical point is studied in the Creutz cellular automaton. The Fourier heat law is confirmed to hold in this model by a direct measurement of heat flow under a temperature gradient. The thermal conductivity is carefully investigated near the critical point by the use of the Kubo formula. As a result, the thermal conductivity is found to take a finite value at the critical point, contrary to some previous works. Equal-time correlation of the heat flow is also analyzed by a mean-field type approximation to investigate the temperature dependence of thermal conductivity. A variant of the Creutz cellular automaton called the Q2R is also investigated and similar results are obtained.