Re: Convergence of the Gram-Charlier expansion

From: Chris Chipot (
Date: Sun Sep 30 2012 - 11:46:58 CDT


you can restate your free energy change,


where /g/(?/U/) is a Gaussian distribution and /H_n /(?/U/) are Hermite

The farthest you are from second-order perturbation theory, the slower the
convergence of your Gram-Charlier expansion.

As for the order, it is pretty much system dependent. Charging a van der
Waals particle will evidently be pretty quick.

Chris Chipot

On 9/30/12 5:34 PM, Ali Khanlarkhani wrote:
> The following sentence come from "ParseFEP Plugin, Version 1.5" manual:
> "Convergence of the Gram-Charlier expansion at a given order
> represents a relevant measure of how well-defined the probability
> distribution is."
> What does it mean? convergence at what order is good?
> Khanlarkhani

Chris Chipot, Ph.D.
Theoretical and Computational Biophysics Group
Beckman Institute
University of Illinois at Urbana-Champaign
405 North Mathews                                 Phone: (217) 244-5711
Urbana, Illinois 61801                            Fax:   (217) 244-6078
The light shines in the darkness, and the darkness has not overcome it.
                                                               John 1:5.

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