[lammps-users] restricted minimizations

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#1

Hi,

i have this system i want to minimize only in the z-direction, that's, i want to leave its x and y atomic coordinates
constant.

Does the minimize command allow for doing this kind of minimizations?

Thanks
Regards
Miguel

#2

I haven't tried it, but I think you could use fix setforce to set the
x,y force components to 0.0, and it would work.

Steve

#3

Steve,

thanks.

Sounds reasonable, but i have a small question. Say i set fx and fy equal
to 0.0, whereas i want fz to change. How does one indicate this with setforce?

setforce 0.0 0.0 seems to not be correct way of doing it.

In the manual i only see two possibilities: using NULL or using a variable.
NULL is not what i want, since this let that force with its current value.
As for the variable, i'm not sure this is either what i want.

Thanks
Regards
Miguel

#4

Miguel,

You probably want something like this:

fix 1 all setforce 0.0 0.0 NULL

Paul