Friday, March 31, 2017

particle physics - Is there a connection between the fluctuation-dissipation theorem and the Green–Kubo relations?


Is there a connection between the fluctuation-dissipation theorem and the Green–Kubo relations? I have a hard time finding out if there is a relation and what it is, because the fluctuation-dissipation theorem always seems to be stated in another way and for specific cases. Both formula seem to be a statement about how a macroscopic property is determined as an integral over Greens function'esque objects.


What is the exact relation and the hierarchy of the two concepts?



Answer



The fluctuation-dissipation theorem is a general principle that comes in many concrete forms. It expresses in each case a way how the spectrum of equilibrium fluctuations can be probed by applying weak external fields.


The Kubo relations are just one specific instance of it.


For example, Linda E. Reichl derives in her book on statistical physics the F/D theorem in Section 15D from general principles of nonequilibrium thermodynamics, and gives several quantitative applications, before she gives in Section 15H the Kubo relation as the microscopic expression for it.


No comments:

Post a Comment

classical mechanics - Moment of a force about a given axis (Torque) - Scalar or vectorial?

I am studying Statics and saw that: The moment of a force about a given axis (or Torque) is defined by the equation: $M_X = (\vec r \times \...