deform or change_box modify atomic coordinates also with remap none

In the attached simple example three molecules are in a cell being tilted by fix_deform with remap none. No force acts on the atoms, but during the deformation one molecule continuously shifts towards -X. I would expect that atomic coordinates stay unchanged during the whole simulation. Also, why just one molecule moves?

I report the script also below.

Thanks in advance for any reply.

units lj
atom_style molecular
dimension 2
boundary p p p


pair_style lj/cut 1.0
pair_coeff * * 0.0 0.0

change_box all triclinic

dump mydump all custom 100 dump.dump id type xu yu
dump_modify mydump sort id append no first yes

velocity all set 0. 0. 0.

fix deform all deform 1 xy vel 1e-1 remap none units box
fix 2D all enforce2d
fix NVE all nve

run 3000 (347 Bytes)

example.lmp (484 Bytes)