From: Giacomo Fiorin (
Date: Thu May 25 2017 - 09:19:09 CDT

The command is working correctly, but if you are trying to make AP1 and AP2
stay at their nearest periodic image to each other, wrapping by fragment
won't help, because they will be wrapped independently.

You should try centering the trajectory on one of the segments (provided
that it's written contiguously in the first place).


On Thu, May 25, 2017 at 3:13 AM, Peter Mawanga <> wrote:

> Hello to all
> I am trying to remove sudden RMSD jumps between two segments (AP1 and
> AP2), observed as an artefact of periodic conditions.
> I have tried the commands below (or similar variations), but have not been
> able to resolve this:
> pbc unwrap -sel "segname AP1 AP2"
> pbc wrap -all -sel "segname AP1 AP2" -compound fragment -compoundref
> "segname AP1 AP2" -center unitcell -centersel "segname AP1"
> I think this should be working as per the PBCTools manual:
> Please let me know if there is any error or some omission in the commands.
> Feel free to ask for further information.
> --
> Cheers
> Peter

Giacomo Fiorin
Associate Professor of Research, Temple University, Philadelphia, PA
Contractor, National Institutes of Health, Bethesda, MD