The NAMD Plot plugin provides an easy-to-use interface for plotting energy, volume, and other statistics reported in NAMD log files during a simulation. The functionality is similar to that provided by the 'namdplot' shell script included with NAMD, but uses other VMD plugins to do the plotting so no extra software is required.
This video explains how to use NAMD plot.
More details and information can be found here :
https://www.ks.uiuc.edu/Research/vmd/plugins/namdplot/
