[gmx-users] doubt about constrain

Mark Abraham Mark.Abraham at anu.edu.au
Sat Jan 12 03:43:24 CET 2008

sudheer babu wrote:
> hi gmx users,
> i have one doubt regarding constriants,i want to do production run of 
> popc in water. In my pr.mdp file i have used constraints of all-bonds,
> but in case of production which type of constriants i have to use ? i 
> have checked gmx archives some people used "all-bonds" constraints, some 
> people used "none" contraints and some other people used "H-bonds" 
> constraints in md.mdp file of membranes.
> which type of constraint i have to opt??
> anyone help me pls

That depends what you want your simulation to tell you, and how long a 
timestep you want to use. The more constraints you have, the fewer 
short-period motions there are and the longer an integration timestep 
you can get away with. However if you are looking for fine detail of 
atomistic behaviour this might be too high a price to pay.


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