Free-energy calculations - Theoretical Biophysics Group

Free-energy perturbation calculations “Alchemical transformations”
∆Ahydration can be also obtained from the reverse process,
in which solute–solvent interactions are turned off.
This corresponds to moving the solute from the aqueous
solution to the gas phase. and the calculated quantity is
the negative of ∆Ahydration.
If the same order parameter, λ, is used for the forward
and the reverse transformations, the changes in
the free energy with λ should be reversible, and, consequently,
the sum of the calculated free energies differences
should be zero.
Chris Chipot Free-energy calculations