Free energy tutorial

GROMACS version: 5.1.4
GROMACS modification: Yes/No
Dear Justin,
I studied your tutorial entitle of " Free Energy Calculations: Methane in Water", I want to know what bound state did you use in this tutorial for the methane?
Best regards,

I don’t follow the question. There is no “bound” state in an absolute free energy of solvation. The reference state is the gas phase, which is achieved by not decoupling intramolecular interactions as a function of λ.