[gmx-developers] remove periodicity

[Gaurav Goel]

If I know the coordinates at time 't-del_t' and 't', I can remove the
periodicity as follows:
  /* Remove periodicity */
...
...

      while(xcur[ind][m]-xprev[ind][m] <= -hbox[m])
	rvec_inc(xcur[ind],box[m]);
      while(xcur[ind][m]-xprev[ind][m] >  hbox[m])
	rvec_dec(xcur[ind],box[m]);
...
...

-> If I only know the coordinates at 't', is it still possible to
remove periodicity?
In the update() subroutine, I want to be able to make a list of all
atoms within a thin slab at a fixed distance from the edge of the box.
E.g., all particles in a slab of width L/10, with the x-coordinate of
the center of slab at a distance L/4 from the yz-face of box.

thanks,
Gaurav