[gmx-users] Re: abnormal flip-flop when embedding cholesterol into DOPC using CG

[Ran Friedman]

Dear Xavier, GMX users,

Xavier Periole wrote:
> One other thing. In the CG FF the time step is considered as part of the
> force field. Meaning that you should not play with it too much.
> 0.04-0.02 ps is the actual range where the force field is considered
> to reproduce experimental values of various quantities used for
> paraameterization of the FF. Outside this range you change the balance
> between the different terms and thus would alter the quality of the FF.
Can you elaborate on this a bit? Surely if one changes the temperature,
pressure, compressibility, threshold distances etc., one doesn't
necessarily reproduces the experimental results. Too long timesteps may
also cause a problem. But why would it be wrong to use a shorter time
step here?

Ran.