The Fluctuation-Dissipation Theorem in Phase Transition: Fisher Exponent from the Perspective of Fractal Dynamics
Monte Carlo, Fluctuation-Dissipation Theorem, Disordered Ising Model, Fractal Dynamics
In this work, we develop the hypothesis that the dynamics of a certain system may cause activity to be restricted to a subset of space, characterized by a fractal dimension df smaller than the spatial dimension d. In this way, we recover the fluctuation-dissipation theorem near a phase transition. We also explain the origin of the Fisher exponent and address how the response function can be sensitive to changes in dimensionality, which affects all critical exponents. We discuss how this phenomenon is observable in growth processes and near critical points for equilibrium systems. In particular, we determine the fractal dimension df for the disordered Ising model and validate it through computational simulations for two dimensions using parallel programming.