Comment on "Fluctuation-dissipation relations in the nonequilibrium critical dynamics of Ising models"

TL;DR

This paper critically examines Mayer et al.'s method for calculating fluctuation-dissipation ratios in nonequilibrium critical systems, revealing that their key quantities are actually independent of waiting time and determine the observed linear behavior.

Contribution

The paper clarifies the nature of the quantities used in fluctuation-dissipation ratio calculations, showing they are one-time, time-independent values, challenging previous interpretations.

Findings

Key quantities are one-time, independent of waiting time.

The ratio of these quantities explains the linear fluctuation-dissipation plots.

Challenges the interpretation of fluctuation-dissipation ratios in the cited work.

Abstract

Recently Mayer et al. [Phys. Rev. E {\bf 68}, 016116 (2003)] proposed a new way to compute numerically the fluctuation-dissipation ratios in nonequilibrium critical systems. Using well-known facts of nonequilibrium critical dynamics I show that the leading contributions of the quantities they consider are in fact one-time quantities which are independent of the waiting time. The ratio of these one-time quantities determines the slope of the straight lines observed in the fluctuation-dissipation plots of Mayer et al.