[gmx-users] Problem with dihedral restraints

[Mark Abraham]

Hi,

You should expect changes, you're not freezing the angles in place. You're
making it less energetically favourable for them to change. But if the
environment is strong enough, they'll respond to that. Increase kfac by a
factor of a thousand and they'll probably not move noticeably. Whether that
is a good idea is something you might find out later :-)

Mark

On Fri, Aug 4, 2017 at 4:16 PM gangotri dey <holyriver6 at gmail.com> wrote:

> Hello!
>
> I posted a question a few days back and I got a reply but it still does not
> work.
>
> I have a small drug molecule that I would like to compute. I want to
> restraint the Ramachandran dihedral angles. I have used the following lines
> in the .itp file for the molecule. It was suggested that I increase the
> force constant, which I did. However, I still see the change in the
> dihedral angles after the NVT, NPT and Production run. I am not sure how
> best it can be implemented.
>
>
>
> [ dihedral_restraints ]
> ; ai   aj    ak    al  type  phi  dphi  kfac
> 698 702 692 691 1 -142.56 0 100
> 719 712 716 698 1 -84.24 0 100
>
> 702    698    716    712     1    50.3766     0 100
> 695    691    692    702     1  -166.8294     0 100
>
>
> My .mdp file is similar to the one used in the Bevan lab tutorial online.
>
>
>
>
> *Thank you*
>
> *Gangotri Dey*
> --
> Gromacs Users mailing list
>
> * Please search the archive at
> http://www.gromacs.org/Support/Mailing_Lists/GMX-Users_List before
> posting!
>
> * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
>
> * For (un)subscribe requests visit
> https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or
> send a mail to gmx-users-request at gromacs.org.
>