[gmx-users] pressure scaling more than 1%

[Mark Abraham]

Wang Qin wrote:
> Dear all,
>           I am trying to do a FEP. In the equilibrium step, it fails 
> after about 500 steps with a warnning:  pressure scaling more than 1%, 
> mu: 1.06718 1.06718 1.06718. I searched the old discussion about it and 
> then try to increase the tau_p to 2 till 10. But it just goes futher but 
> still meets the problem at the end.
>           Any idea about it?

Not unless you tell us how you prepared this system. Almost certainly 
the initial structure is too far from the constant-P equilibrium state. 
Follow the kind of things that the tutorial material does, and also 
check out this link 
http://wiki.gromacs.org/index.php/Steps_to_Perform_a_Simulation

Mark