[gmx-users] FEP with real or dummy charges?
Georgios Patargias
G.N.Patargias at leeds.ac.uk
Wed May 23 16:12:23 CEST 2007
Thanks again for the reply. A virtual point charge
is what I want.
Best wishes
George
-----Original Message-----
From: gmx-users-bounces at gromacs.org on behalf of Maik Goette
Sent: Wed 5/23/2007 12:51 PM
To: Discussion list for GROMACS users
Subject: Re: [gmx-users] FEP with real or dummy charges?
No.
I said, you may want to perturb all partial charges in the site, where
the netto +1 charge sits OR place a virtual site somewhere in between,
to grow a point charge, whereas I'm not sure, if a point charge is, what
you want.
Regards
Maik Goette, Dipl. Biol.
Max Planck Institute for Biophysical Chemistry
Theoretical & computational biophysics department
Am Fassberg 11
37077 Goettingen
Germany
Tel. : ++49 551 201 2310
Fax : ++49 551 201 2302
Email : mgoette[at]mpi-bpc.mpg.de
mgoette2[at]gwdg.de
WWW : http://www.mpibpc.gwdg.de/groups/grubmueller/
Georgios Patargias wrote:
> Many thanks for your reply! Concerning the use of PME, I
> also put a counter charge in bulk in order to keep the whole
> cell neutral.
>
> So, if I understood corectly, you suggest that I should perturb
> all the partial charges around the vitual site?
>
> George
>
>
>
>
> -----Original Message-----
> From: gmx-users-bounces at gromacs.org on behalf of Maik Goette
> Sent: Sat 5/19/2007 12:53 PM
> To: Discussion list for GROMACS users
> Subject: Re: [gmx-users] FEP with real or dummy charges?
>
> I don't really know, if this may solve your problem, but what I want to
> suggest is, not using PME for the simulation. I don't know, how other
> longerange-methods behave while changing the total charge of the system,
> PME won't work (as far, as I know).
>
> Concerning your way, how to perturb the charge, it depends on, where you
> think the charge sits...In general, I would assume, that a site, where a
> netto charge is 0 and the same, where the netto charge is one, will be
> different in partial charges of most atoms in the area. Therefore
> perturbing the whole site (just the partial charges) would be the right
> way to do it. This in fact means, that you have the partial charges for
> the +1-charge atoms...maybe spreading the charge in a senseful way,
> should do it.
>
> Using a virtual site would be the solution for a point charge in space,
> its coordinates relative to two or more atoms.
>
> If you want to have the charge sitting on a special atom, just change
> that charge explicitly, although I'm really not sure, if that's the way,
> one should go.
>
> Hope you get some help from that.
>
> Regards
>
> Maik Goette, Dipl. Biol.
> Max Planck Institute for Biophysical Chemistry
> Theoretical & computational biophysics department
> Am Fassberg 11
> 37077 Goettingen
> Germany
> Tel. : ++49 551 201 2310
> Fax : ++49 551 201 2302
> Email : mgoette[at]mpi-bpc.mpg.de
> mgoette2[at]gwdg.de
> WWW : http://www.mpibpc.gwdg.de/groups/grubmueller/
>
>
> Georgios Patargias wrote:
>> Hi
>>
>> I want to calculate the change in free energy (electrostatic contribution only)
>> when introducing a charge in a certain site of a protein using a single step
>> FEP.
>>
>> Should this be done with charging an inserted virtual site (a dummy atom) or a
>> protein atom (e.g. Ca)?
>>
>> I noticed that in the case of the dummy atom, the Coul-14:Protein-vsite zero. I am
>> not sure why though...
>>
>> Thanks a lot in advance for any feedback.
>>
>> Best wishes
>> George
>>
>> Dr. George Patargias
>> Polymer IRC Group
>> University of Leeds
>> Leeds, LS2 9JT, UK
>>
>> _______________________________________________
>> gmx-users mailing list gmx-users at gromacs.org
>> http://www.gromacs.org/mailman/listinfo/gmx-users
>> Please search the archive at http://www.gromacs.org/search before posting!
>> Please don't post (un)subscribe requests to the list. Use the
>> www interface or send it to gmx-users-request at gromacs.org.
>> Can't post? Read http://www.gromacs.org/mailing_lists/users.php
>>
>> .
>>
> _______________________________________________
> gmx-users mailing list gmx-users at gromacs.org
> http://www.gromacs.org/mailman/listinfo/gmx-users
> Please search the archive at http://www.gromacs.org/search before posting!
> Please don't post (un)subscribe requests to the list. Use the
> www interface or send it to gmx-users-request at gromacs.org.
> Can't post? Read http://www.gromacs.org/mailing_lists/users.php
>
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> gmx-users mailing list gmx-users at gromacs.org
> http://www.gromacs.org/mailman/listinfo/gmx-users
> Please search the archive at http://www.gromacs.org/search before posting!
> Please don't post (un)subscribe requests to the list. Use the
> www interface or send it to gmx-users-request at gromacs.org.
> Can't post? Read http://www.gromacs.org/mailing_lists/users.php
_______________________________________________
gmx-users mailing list gmx-users at gromacs.org
http://www.gromacs.org/mailman/listinfo/gmx-users
Please search the archive at http://www.gromacs.org/search before posting!
Please don't post (un)subscribe requests to the list. Use the
www interface or send it to gmx-users-request at gromacs.org.
Can't post? Read http://www.gromacs.org/mailing_lists/users.php
-------------- next part --------------
A non-text attachment was scrubbed...
Name: winmail.dat
Type: application/ms-tnef
Size: 4924 bytes
Desc: not available
URL: <http://maillist.sys.kth.se/pipermail/gromacs.org_gmx-users/attachments/20070523/a28dc4a4/attachment.bin>
More information about the gromacs.org_gmx-users
mailing list