Do free energy simulations with AWH require multiple simulations

User discussions
1

GROMACS version: 2023.2
GROMACS modification: No
I was reading the tutorial on how to use AWH in the free of solvation simulation.(Calculating free energy — GROMACS tutorials https://tutorials.gromacs.org documentation) I’m not sure if I have over read something but there were no mentions of using multiple simulations for each λ state. Does that mean that you don’t have to? Or do they already expect you to know that and that’s why they don’t mention it. If it’s the former, why not?

2

Hi,
Performing alchemical transformation with AWH does not required to run a simulation for each lambda point, but the transformation occurs in one simulation. Does this answer your question?
You could try to run the jupiter-notebook online by clicking to “run a free online interactive binder” at MyBinder on Free energy of solvation using AWH method — GROMACS tutorials https://tutorials.gromacs.org documentation . It will take several minutes to launch.
\Alessandra

3

So if I understand correctly, it transitions between λ states in the same simulation? So is more like a standard MD simulation with free energy elements?

4

Hi,
yes the alchemical transformation from lambda 0 to lambda 1 occurs in one simulation run, with an mdp file where the option awh and free energy are active.
See more on the method in here and connected link (e.i webinar)
https://www.gromacs.org/topic/awh-fep.html
I hope it helps
/Alessandra