Dear All,

I am trying to calculate the fractional free volume (FFV) of a polymer in the presence of a solvent using molecular dynamics.I have already performed Forcite MD simulations on a system containing both polymer and solvent. My question is: When calculating FFV, should I:

1. Use the full equilibrated polymer + solvent configuration directly, or

2. Remove the solvent molecules and calculate FFV using only the polymer structure?

   More specifically, I want to understand which approach better represents the physically meaningful free volume of the polymer in a swollen state, and how each method affects the interpretation of accessible vs intrinsic free volume.

   Thank you

   Hakkim