Hi,

I would like to calculate cohesive energy density in Gromacs for my **(polymer/water)** system. I found a formula which get the CED.(The formula is attached here)

But, I dont know exactly what are the parameters.

The article stated that:

where E is the total potential energy in vacuum and in the

condensed state, respectively, and V is the molar volume of material

in its condensed state.

But I don’t know the difference between vacuum and condensed state. Is vacuum state a box with just polymer without water and condensed state a box with water and polymer? how can I get potential energy then? `gmx energy`

? Could you please help me with that?

Thanks a lot