[gmx-developers] Regd. Changing force calculation

[Daniele Bemporad]

Hi Anjan
If I understand correctly your e-mail, you want to use something else
than the standard potential energy terms in gromacs. When running mdrun
(I have no clue for other types of calculations, e.g. minimization), you
use subroutine do_md (in file src/kernel/md.c) which calls do_force (in
src/mdlib/sim_util.c) which in turn calls force (in file
src/mdlib/force.c). I would say this is the key subroutine. It calls
calc_bonds (which calculates the bonded interactions, in file
src/gmxlib/bondfree.c) and do_fnbf (which calculates the non-bonded
interactions, in file src/gmxlib/fnbf.c). The latter uses the inner
loops, some of which written in assembly and some others written during
the compilation by src/gmxlib/mkinl*.c files. If you want to modify the
potential energy function, then either modify the above subroutines or
disable them and write your own for instance inside force.c.
Corrections/comments from the authors of the program are wellcome.
Hope this helps.
Daniele

On Wed, 25 Jun 2003, Anjan Raghunathan wrote:

> Hi,
>   I'd like to know which function(s) to modify if I need to
> use a separate force calculating(and potential) function of my
> own at every timestep in GROMACS. Could anyone point out the
> functions that are this particular force function call
> dependent and which function I should modify?
>
> thanks,
>
> Anjan
> _______________________________________
>
> Anjan V. Raghunathan
> Graduate Research Assistant
> Computational Electronics Group
> 3213 Beckman Institute,
> Univ. of Illinois at Urbana-Champaign.
>
> E-mail:araghuna at uiuc.edu
> Off: 217-244-1964
> Res: 217-355-5418
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