I did a free energy calculation based on the BAR method (in GROMACS) and now I want to see the entropic and enthalpic contribution of that free energy. How could it be done with molecular simulation?
Thank you in advance!
Wojciech Kopec
Isn't entropy, at least in part, implicitly included in the ensemble average?
To obtain the enthalpy and entropy contribution, you can calculate the free energy of solvation at several temperatures then draw the curve between dG as y versus temperature as x. If the temperatures range is not too large, the line should be linear. Then, you can get the dS from the -slope and the dH from the extrapolation of dG (y) at x = 0.
You can refer to this publication for more detail. Article Characterization of the TIP4P-Ew water model: Vapor pressure...
It is actually for the evaporation process, but the ideas will be the same. The method in the publication is quite complex, but I think you can estimate the contribution of enthalpy and entropy from the linear regression of dG = dH - TdS easily.
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