[gmx-users] dihedral restraints

Jessica Leuchter jessica.leuchter at gmail.com
Mon Mar 23 16:29:51 CET 2015


Do you also change the angle to where you want to constrain it to? Or just
the kfac?

On Mon, Mar 23, 2015 at 5:27 PM, Andrew Ritchie <drew.w.ritchie at gmail.com>
wrote:

> "It will depend on the force field parameters for each set of 4 atoms and
> how much or little you want to allow them to fluctuate."
> I forgot to mention, the local environment also matters.
>
> On Mon, Mar 23, 2015 at 10:23 AM, Andrew Ritchie <drew.w.ritchie at gmail.com
> >
> wrote:
>
> > It will depend on the force field parameters for each set of 4 atoms and
> > how much or little you want to allow them to fluctuate.  If you want to
> > allow some movement, some experimentation is required.  If you want them
> to
> > essentially not move, just chose an arbitrarily large number.  When I
> want
> > to remove essentially all dihedral movement, I typically choose ~ 1000
> > (kJ/mol/rad^2) and see very little movement.  When I'm doing umbrella
> > sampling about a dihedral, I typically use 50-70 (kJ/mol/rad^2).
> >
> > On Mon, Mar 23, 2015 at 9:47 AM, Jessica Leuchter <
> > jessica.leuchter at gmail.com> wrote:
> >
> >> To get the dihedrals to stay restrained to their original values what
> >> should the kfac be?
> >>
> >> On Fri, Mar 20, 2015 at 3:04 PM, Justin Lemkul <jalemkul at vt.edu> wrote:
> >>
> >> >
> >> >
> >> > On 3/20/15 9:00 AM, Jessica Leuchter wrote:
> >> >
> >> >> Dear All,
> >> >>
> >> >> I would like to add dihedral restraints to 10 residues in my topology
> >> >> file using the newest version of gromacs.  I have done the
> >> >> following(see below) to my topology file. And this is the *grompp
> >> >> command* I am using: gmx grompp -f ions.mdp -c 1AKI_solv.gro -p
> >> >> topol.top -o ions.tpr. But I am getting the error message below.
> >> >>
> >> >> *topol.top file*:
> >> >>
> >> >> [ dihedral_restraints ]
> >> >> ;  ai       aj    ak      al        fnID    phi    dphi    kfac
> >> >>
> >> >>   1497  1499  1509  1511     9    -70.488     0       1
> >> >>   1499  1509  1511  1513     9    -12.561     0       1
> >> >>   1511  1513  1515  1518     9     95.706     0       1
> >> >>   1513  1515  1518  1520     9   -117.614     0       1
> >> >>   1518  1520  1522  1530     9   -111.163     0       1
> >> >>   1520  1522  1530  1532     9    -72.034     0       1
> >> >>   1530  1532  1534  1542     9   -108.627     0       1
> >> >>   1532  1534  1542  1544     9   -103.437     0       1
> >> >>   1542  1544  1554  1556     9    -80.981     0       1
> >> >>   1544  1554  1556  1558     9     46.231     0       1
> >> >>   1556  1558  1560  1570     9   -107.016     0       1
> >> >>   1558  1560  1570  1572     9     20.452     0       1
> >> >>   1570  1572  1574  1587     9    -82.626     0       1
> >> >>   1572  1574  1587  1589     9    169.300     0       1
> >> >>   1587  1589  1591  1608     9    -82.868     0       1
> >> >>   1589  1591  1608  1610     9    -47.555     0       1
> >> >>   1608  1610  1612  1623     9    -39.285     0       1
> >> >>   1610  1612  1623  1625     9    -72.644     0       1
> >> >>   1623  1625  1627  1642     9     -7.261     0       1
> >> >>   1625  1627  1642  1644     9    -51.880     0       1
> >> >>   1642  1644  1646  1652     9    -38.845     0       1
> >> >>   1644  1646  1652  1654     9    -73.856     0       1
> >> >>
> >> >>
> >> >> *Fatal error:*
> >> >> Incorrect number of parameters - found 2, expected 3 or 6 for Dih.
> >> Rest..
> >> >> For more information and tips for troubleshooting, please check the
> >> >> GROMACS
> >> >> website at http://www.gromacs.org/Documentation/Errors
> >> >>
> >> >>
> >> > Your restraints directive uses the wrong format.  See manual section
> >> > 5.7.1, which has a complete example of dihedral restraints and an
> >> > explanation of all the required columns.
> >> >
> >> > -Justin
> >> >
> >> > --
> >> > ==================================================
> >> >
> >> > Justin A. Lemkul, Ph.D.
> >> > Ruth L. Kirschstein NRSA Postdoctoral Fellow
> >> >
> >> > Department of Pharmaceutical Sciences
> >> > School of Pharmacy
> >> > Health Sciences Facility II, Room 629
> >> > University of Maryland, Baltimore
> >> > 20 Penn St.
> >> > Baltimore, MD 21201
> >> >
> >> > jalemkul at outerbanks.umaryland.edu | (410) 706-7441
> >> > http://mackerell.umaryland.edu/~jalemkul
> >> >
> >> > ==================================================
> >> > --
> >> > Gromacs Users mailing list
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> >> >
> >>
> >>
> >>
> >> --
> >> Jessica Leuchter
> >> Wake Forest University 2014
> >> 954.591.2222
> >> --
> >> Gromacs Users mailing list
> >>
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> >
> >
> >
> > --
> > -Andrew Ritchie
> >
>
>
>
> --
> -Andrew Ritchie
> --
> Gromacs Users mailing list
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-- 
Jessica Leuchter
Wake Forest University 2014
954.591.2222


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