[gmx-users] constraint error

[Anton Feenstra]

xiaoyi li wrote:
> Could you tell me why I should run md 'without' pressure coupling first?
> Could I run it with pressure coupling first, then EM, then long time md
> run?

If your system is far from equilibrium, you may get large forces. Those
will influence the pressure, which will get 'corrected' by the pressure
coupling. If this correction is too large, it may actually make things
worse (since the pressure wasn't the problem in the first place - it was
a non-equilibrated system). So, by turning off p-couple you prevent that
and allow your system to reach a (better) equilibrated stage on its own
first. Then, you can safely start equilibrating pressure also.


-- 
Groetjes,

Anton
  _____________ _______________________________________________________
|             |                                                       |
|  _   _  ___,| K. Anton Feenstra                                     |
| / \ / \'| | | Dept. of Pharmacochem. - Vrije Universiteit Amsterdam |
|(   |   )| | | De Boelelaan 1083 - 1081 HV Amsterdam - Netherlands   |
| \_/ \_/ | | | Tel: +31 20 44 47608 - Fax: +31 20 44 47610           |
|             | Feenstra at chem.vu.nl - www.chem.vu.nl/~feenstra/       |
|             | "If You See Me Getting High, Knock Me Down"           |
|             | (Red Hot Chili Peppers)                               |
|_____________|_______________________________________________________|