[gmx-users] COM pulling: Reference position in space

[Quyen Vu Van]

Dear GMX community,
I read on manual of gromacs that the reference group in pulling code can be
defined by absolute position in space.

How can I change my setup for that purpose, for example the coordinate of
reference point X0 Y0 Z0
; Pull code
pull                    = yes
pull_ncoords            = 1         ; only one reaction coordinate
pull_ngroups            = 2         ; two groups defining one reaction
coordinate
pull_coord1_groups      = 1 2
pull_group1_name        = ACE
pull_group2_name        = CB50ALA
pull_coord1_type        = umbrella  ; harmonic potential
pull_coord1_geometry    = direction ; simple distance increase
pull-coord1-vec         = -1.0 0.0 0.0
pull_coord1_start       = yes       ; define initial COM distance > 0
pull_coord1_rate        = 0.005      ; 0.005 nm per ps = 5 nm per ns
pull_coord1_k           = 1000      ; kJ mol^-1 nm^-2
Best regards,
Quyen