[gmx-developers] Umbrella code extension / flat bottom potential

Szilárd Páll pall.szilard at gmail.com
Fri Feb 13 15:35:52 CET 2015


...and please, don't forget to give it a +1 verifyed (click on reply)
if it work as expected!
--
Szilárd


On Fri, Feb 13, 2015 at 3:17 PM, Sabine Reisser <sabine.reisser at kit.edu> wrote:
> Hi Berk,
>
> thank you, excellent!
> When will this be available?
>
> Cheers
> Sabine
>
>
> Am 13.02.2015 14:58, schrieb Berk Hess:
>
> Hi,
>
> Does https://gerrit.gromacs.org/#/c/3947/ do what you want?
>
> Cheers,
>
> Berk
>
> On 2015-02-13 14:41, Sabine Reisser wrote:
>
> Hi again,
>
> I think this topic is still interesting.
> I have just tested Jochens code for flat-bottom position restraints, which
> works great, but unfortunately it's not suitable for what I need.
> Here, you can define a layer (with normal in z-direction) with a certain
> thickness and invert the restraints. The problem is that you cannot define a
> reference position for the layer, but the reference position is always the
> initial geometry. That way, particles are pushed away from the layer, but
> the direction is not defined. So I cannot use this to bind my peptides to
> one leaflet of the membrane (cmp. my post "Flat bottom position restraints"
> on gmx-users). Also I cannot use it to restrain distances between molecules,
> which I also need sometimes.
>
> So I'd be grateful if you could reconsider including the extension to the
> pull code described below.
>
> Cheers
> Sabine
>
>
>
>
>
> --------------------------------------------------------------------------------------
>
> I guess you mean flat-bottomed position restraints.
> I am talking about the pull code (between COM iso atoms).
>
> Berk
>
> On 02/13/2014 04:05 AM, Mark Abraham wrote:
>> It's been in master branch for about a year :-)
>>
>> Mark
>>
>>
>> On Wed, Feb 12, 2014 at 8:20 PM, Berk Hess <hess at kth.se
>> <mailto:hess at kth.se>> wrote:
>>
>>     On 02/12/2014 04:55 PM, David van der Spoel wrote:
>>
>>         On 2014-02-12 15:24, Sabine Reisser wrote:
>>
>>             Hi,
>>
>>               "It seems like your potential would not need an extra
>>             parameter (it
>>             should
>>             equal a flat bottomed potential with lower limit 0)."
>>
>>         A flat bottom potential is already in the code and we have
>>         used it extensively. Jochen Hub has implemented it.
>>
>>     Not in the main distribution.
>>
>>     Cheers,
>>
>>     Berk
>>
>>
>>             Yes, this is exactly what I mean.
>>
>>             Thanks & cheers
>>             Sabine
>>
>>
>>
>>             On 02/12/2014 03:08 PM, Berk Hess wrote:
>>
>>                 Hi,
>>
>>                 This indeed looks like a flat-bottomed restraint
>>                 potential. I had
>>                 proposed that addition to the pull code for 5.0 in a
>>                 request for
>>                 feedback, which I also posted to the developers list.
>>                 But since I didn't
>>                 receive any response on this point I didn't implement
>>                 it. Also because a
>>                 general flat bottomed potential needs an extra
>>                 (distance) parameter. It
>>                 seems like your potential would not need an extra
>>                 parameter (it should
>>                 equal a flat bottomed potential with lower limit 0).
>>                 Since it's too late
>>                 for 5.0, I would propose to implement the flat
>>                 bottomed potential for
>>                 5.1.
>>
>>                 Cheers,
>>
>>                 Berk
>>
>>                 On 02/12/2014 02:31 PM, Shirts, Michael (mrs5pt) wrote:
>>
>>                     Hi, Sabine-
>>
>>                     So, this looks like the distance restraint
>>                     potential (bond function
>>                     10) in
>>                     section 4.3.4 of the manual that matches this
>>                     potential function.  Right
>>                     now, this potential can only be applied.  However,
>>                     there is a planned
>>                     fix
>>                     for 5.0 that will include the ability to add all
>>                     bonded interactions in
>>                     between arbitrary atoms in the system, even if
>>                     they are not in the same
>>                     molecule.
>>
>>                     I BELIEVE there is an extension to the pull code
>>                     that would allow
>>                     general
>>                     bonded potentials to be used between COMs of index
>>                     groups as well but
>>                     I'm
>>                     not as certain about that.
>>
>>                     I think that these planned changes will capture
>>                     the functionality
>>                     that you
>>                     are describing.  Is that correct?
>>
>>                     Best,
>>
>>                     ~~~~~~~~~~~~
>>                     Michael Shirts
>>                     Assistant Professor
>>                     Department of Chemical Engineering
>>                     University of Virginia
>>                     michael.shirts at virginia.edu
>>                     <mailto:michael.shirts at virginia.edu>
>>                     (434)-243-1821
>>
>>
>>
>>                     On 2/12/14, 8:20 AM, "Sabine Reisser"
>>                     <sabine.reisser at kit.edu
>>                     <mailto:sabine.reisser at kit.edu>> wrote:
>>
>>                         Hello,
>>
>>                         I have implemented an extension to the
>>                         existing umbrella code in
>>                         Gromacs
>>                         version 4.6.3. It is a semiharmonic potential
>>                         which sets a maximum
>>                         distance between two index groups. When this
>>                         distance is trespassed, a
>>                         force kicks in and bounces the pull group
>>                         back, when the distance is
>>                         below the threshold, motions are completely
>>                         unrestrained. I use this
>>                         code to simulate pores of antimicrobial
>>                         peptides, to keep the peptides
>>                         in close vicinity without actually interfering
>>                         with the pore formation
>>                         process.
>>                         The code can also be used to make sure several
>>                         peptides bind to the
>>                         same
>>                         side of a membrane or in ligand-binding
>>                         simulations.
>>                         The relevant part of the extended code is no
>>                         longer than 10 lines,
>>                         but I
>>                         naturally had to change other files in order
>>                         to read the modified input
>>
>>                     >from the mdp files, too. Affected binaries are
>>                     mdrun and grompp.
>>
>>                         Instead of providing this singular modified
>>                         Gromacs 4.6.3 as a tarball
>>                         for downloading, I would like to get this
>>                         extension into the official
>>                         release so that it is maintained also in
>>                         future releases.
>>
>>                         What is the procedure to achieve this or who
>>                         is the best person to
>>                         address?
>>
>>                         With best regards
>>
>>                         Sabine Reißer
>>
>>
>>                         ---------------------------------
>>                         Dipl. phys. Sabine Reißer
>>                         Theoretical Chemical Biology
>>                         Institute for Physical Chemistry
>>                         Karlsruhe Institute for Technology (KIT)
>>                         Germany
>>
>>
>>
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> Dipl. Phys. Sabine Reißer
> Karlsruhe Institute of Technology (KIT)
> Institute of Physical Chemistry
>
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>
>
>
>
>
> --
> Dipl. Phys. Sabine Reißer
> Karlsruhe Institute of Technology (KIT)
> Institute of Physical Chemistry
>
> Phone +49 (0) 721 / 608-45070
>
>
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