[gmx-users] shift the LJ potential

[Mark Abraham]

Hi,

On Mon, Oct 9, 2017 at 5:26 PM Faezeh Pousaneh <fpoosaneh at gmail.com> wrote:

> Hi Mark,
>
> I have a given function for pseudo hard-sphere potential,


There's no ability for GROMACS to support a true hard-sphere potential,
because for such potentials the force is always zero or undefined.

which has
> different powers than LJ and a constant. I have to insert the constant in
> order to properly define the cut-off for my hard spheres.
> I just realized that I can use "user-specified potential". I guess I can
> include the constant there, yes?
>

Yes, if anything is possible, then that's what you should do.


> One more thing, I need to have my own particles, spheres with a diameter
> "a". How can I have them in gromacs?
>

You'd need to write that code ;-)

Mark


> On Oct 9, 2017 3:44 PM, "Mark Abraham" <mark.j.abraham at gmail.com> wrote:
>
> Hi,
>
> Shifting the potential doesn't affect the sampling - only the forces do.
> How does that affect what you're thinking of?
>
> Mark
>
> On Mon, Oct 9, 2017 at 3:14 PM Faezeh Pousaneh <fpoosaneh at gmail.com>
> wrote:
>
> > Hi,
> >
> > I would like to shift the LJ interaction between my particle by a
> constant,
> > (to remove attraction), how can I change the function?
> >
> >
> > Best regards
> > --
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