[gmx-users] which code should I rewrite the function of "position restraints"?

[Makoto Yoneya]

Dear GROMCS users:

I found the following past discussions in the gmx-users ML.

[gmx-users] simulations using structureless surface-2
Mark Abraham mark.abraham at anu.edu.au 
Fri Jul 27 01:56:17 CEST 2007 
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> Dear gmx users,
> my apologies for the previous post. I will try to rephrase my problem.
>
> Is it possible to introduce a plane in a particular direction, for example
> in z direction, where molecules interact with it only based on the
> perpendicular distance between the molecules and the plane?

Yes, this is possible to do, but it is not implemented. Possibly something
in the distance restraints section may do what you want. See the manual.
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I'm considering similar thing and I want to rewrite the GROMACS source code 
relating the "position restraints" (guessing better than "distance
restraints").
Could someone kindly tell me which code(s) should I rewrite to change
consistently
the potential function of the "position restraints".
Thank you for advance.

Makoto Yoneya, Dr.
AIST Tsukuba,
JAPAN