I would like to give my understanding of the pulling method. I don't look into the code either. I am not sure if my understanding is right. Any correction is welcome.
I think the reference point connecting with the pulled group by spring is an COM offset of the reference group. The reference point in fact represents the reference group. Any force induced by spring acts on the pulled group, meanwhile its counter force acts on the reference point (or the reference group). That is why the reference group and the pulled group can be treated equivalently if the simulation system consists of one reference group and one pulled group (see Gromacs Manual). If we don't fix the reference group, the COM of system is stationary. -- View this message in context: http://gromacs.5086.x6.nabble.com/how-is-the-pulling-force-measured-tp5007769p5010387.html Sent from the GROMACS Users Forum mailing list archive at Nabble.com. -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! * Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists