[gmx-users] Pull Code Error "unknown left hand"

Stella Nickerson stella.nickerson at gmail.com
Mon Oct 5 04:25:16 CEST 2015

I am attempting to pull a particle across a simulation box. I did it
several times with version 4.6.3 but this is my first attempting to do it
with version 5.0.4.

I modified my mdp file for the new version based on the updated tutorial (
My pull code looks like this:

; Pull code
pull                    = yes
pull_ngroups            = 2
pull_ncoords            = 1
pull_group1_name        = DMY
pull_group2_name        = DNP
pull_coord1_type        = umbrella
pull_coord1_geometry    = direction_periodic
pull_coord1_groups = 1 2
pull_coord1_dim         = N N Y
pull_coord1_rate        = 0.01
pull_coord1_k           = 1000
pull_start              = yes

I am getting an error message and several warnings. The error reads
"Invalid enum 'yes' for variable pull, using 'no' Next time use one of:
'no' 'umbrella'  'constraint 'constant force.'

The warnings read "unknown left-hand 'pull_ngroups' in parameter file",
with similar warnings for the other left-hand terms.

I tried to compile a version using my old pull code from the earlier
version just to see what would happen and it gave fewer warnings, though it
didn't recognize "pull_vec1." So neither the old options nor the new
options work.

I would love some clarification on this issue.


Stella Nickerson

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