[gmx-users] constraint pulling

[Berk Hess]

>From: Ester Chiessi <ester.chiessi at uniroma2.it>
>Reply-To: Discussion list for GROMACS users <gmx-users at gromacs.org>
>To: Discussion list for GROMACS users <gmx-users at gromacs.org>
>Subject: [gmx-users] constraint pulling Date: Mon, 24 Jan 2005 12:33:49 
>+0100
>
>Hi.
>
>I'd like to make shorter the distance between two groups in my system.
>I used pull code with the following parameters:
>
>verbose = no
>runtype = constraint
>group_1 = a_1537-1544
>reference_group = a_977-984
>constraint_direction = 0 0 1
>constraint_rate = -1
>
>My question is:
>  is it correct to use a constraint_rate <0 to bring nearer groups?

Yes.

>
>If I use 'constraint_rate = 1' the distance between groups become longer,
>but the calculation with 'constraint_rate = -1' give error after about 600
>steps.
>Perhaps the constraint_rate is too high ?

That would be my first guess.
1 nm/ps is quite a high speed.

Berk.

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