[gmx-users] buckingham potentials

Justin A. Lemkul jalemkul at vt.edu
Wed Dec 22 04:53:13 CET 2010



sreelakshmi ramesh wrote:
> I am using gromos force field fotr my work and This force field's files come filled
>  with LJ  functions and now if i want to work with buckingham potential i changed in 
> default section of force field ffG34a21.itp file but it gives me the follwing errors
> 
> 
> ERROR 77 [file ffgmxnb.itp, line 144]:
>   Trying to add LJ (SR) while the default nonbond type is Buck.ham (SR)
> 

You can't simply hack a force field into using a different nonbonded function 
type.  To do so, you'd have to re-write the whole force field.  None of the 
common biomolecular force fields use Buckingham.

-Justin

> any help appreciated.
> 
> 
> On Wed, Dec 22, 2010 at 8:40 AM, Justin A. Lemkul <jalemkul at vt.edu 
> <mailto:jalemkul at vt.edu>> wrote:
> 
> 
> 
>     sreelakshmi ramesh wrote:
> 
> 
>         so if i set vdwtype =cut off and specify 2 in default section (2
>         is for buck and 1 for LJ ) of topology file will gromacs makes
>         suer that i want the calculation with bucking ham potential.
> 
> 
>     Presumably, since that's what the manual would indicate works.  You
>     can answer these sorts of questions yourself by giving it a try,
>     then verifying the run parameters by using gmxdump on the resulting
>     .tpr file.
> 
>     -Justin
> 
>         On Wed, Dec 22, 2010 at 8:32 AM, Justin A. Lemkul
>         <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>> wrote:
> 
> 
> 
>            sreelakshmi ramesh wrote:
> 
>                Thanks a lot for timely reply by gmxusers.I read the
>         manual and
>                i had altered the buckingham coefficients in topolgy
>         file.Now in
>                mdp file in vdwtype i want to specify it as buckingham
>         but looks
>                like i can mention only LJ and in manual they haven't
>         told about
>                the notation for BJ.any suggestions please.
> 
> 
>            Use of Buckingham potentials is not controlled by the .mdp file,
>            except in the fact that several of the vdwtype methods cannot be
>            used in conjunction with Buckingham (see manual, section 7.3.11);
>            only "cutoff" appears to be viable here.
> 
>            -Justin
> 
> 
>                sree.
> 
> 
>                On Tue, Dec 21, 2010 at 6:02 PM, Justin A. Lemkul
>                <jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>
>                <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>
>         <mailto:jalemkul at vt.edu <mailto:jalemkul at vt.edu>>>> wrote:
> 
> 
> 
>                   sreelakshmi ramesh wrote:
> 
>                       can anyone tell me how to alter the parameter B OF
>         buckingham
>                       potential.
> 
> 
>                   Manual, chapter 5, especially table 5.4, which
>         specifically lists
>                   all of the parameters and where they are defined.
> 
>                   -Justin
> 
>                       regards,
>                       sree
> 
> 
>                   --     ========================================
> 
>                   Justin A. Lemkul
>                   Ph.D. Candidate
>                   ICTAS Doctoral Scholar
>                   MILES-IGERT Trainee
>                   Department of Biochemistry
>                   Virginia Tech
>                   Blacksburg, VA
>                   jalemkul[at]vt.edu <http://vt.edu> <http://vt.edu>
>         <http://vt.edu> | (540)
> 
>                231-9080
> 
>                   http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
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>            --     ========================================
> 
>            Justin A. Lemkul
>            Ph.D. Candidate
>            ICTAS Doctoral Scholar
>            MILES-IGERT Trainee
>            Department of Biochemistry
>            Virginia Tech
>            Blacksburg, VA
>            jalemkul[at]vt.edu <http://vt.edu> <http://vt.edu> | (540)
>         231-9080
>            http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
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>     -- 
>     ========================================
> 
>     Justin A. Lemkul
>     Ph.D. Candidate
>     ICTAS Doctoral Scholar
>     MILES-IGERT Trainee
>     Department of Biochemistry
>     Virginia Tech
>     Blacksburg, VA
>     jalemkul[at]vt.edu <http://vt.edu> | (540) 231-9080
>     http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
> 
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-- 
========================================

Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
MILES-IGERT Trainee
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

========================================



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