[gmx-users] Drude force field

[Shraddha Parate]

Hi gmx users!

For polarizable effect, I was setting drude force field in Gromacs
I attempted running Lagrangian Dynamics simulation using Drude force field.
mdp file format was used from the supporting data in below paper.

[2015] Implementation of extended Lagrangian dynamics in GROMACS for
polarizable simulations using the classical Drude oscillator model.(
http://onlinelibrary.wiley.com/doi/10.1002/jcc.23937/abstract;jsessionid=E354008D7BE6AA1A02D26C061B49163A.f02t01
)




-------------------------------------------------------

  ; RUN CONTROL PARAMETERS
  integrator = md-vv

  ; Start time and timestep in ps
  tinit = 0
  dt = 0.001
  nsteps = 10000
  comm-mode = linear
  nstcomm = 100
  comm-grps = System

  ; OUTPUT CONTROL OPTIONS
  nstxout = 1000
  nstvout = 1000
  nstfout = 1000

  ; Output frequency for energies to log file and energy file
  nstlog = 100
  nstcalcenergy = 100
  nstenergy = 100

  ; NEIGHBORSEARCHING PARAMETERS
  cutoff-scheme = verlet
  nstlist = 10
  ns-type = Grid
  pbc = xyz
  rlist = 1.2

  ; OPTIONS FOR ELECTROSTATICS AND VDW
  coulombtype = PME
  rcoulomb = 1.2
  vdwtype = cutoff
  vdw-modifier = potential-switch
  rvdw-switch = 1.0
  rvdw = 1.2
  DispCorr = EnerPres

  ; TEMPERATURE COUPLING
  tcoupl = Nose-Hoover
  nsttcouple = 1
  nh-chain-length = 1

  ; Groups to couple separately
  tc-grps = Atoms Drues
  tau-t = 0.1 0.005
  ref-t = 298.15 1.0

  ; GENERATE VELOCITIES FOR STARTUP RUN, OTHERWISE DO
  ; NOT GENERATE NEW VELOCITIES IF PREVIOUSLY EQUILIBRATED
  gen-vel = yes
  gen-temp = 298.15
  gen-seed = -1

  ; OPTIONS FOR BONDS
  constraints = none ; can also be h-bonds, not all-bonds
  continuation = no


  ; DRUDE PARAMETERS
  drude = yes
  drude-mode = Lagrangian
  drude-t = 1.0
  drude-hardwall = yes
  drude-r = 0.02
  drude-tsteps = 5
-------------------------------------------------------


I couldn't understand [tc-grps = Atoms Drude] option.
If the option is changed to [tc-grps = Protein SOL],I get a fatal error
message.

------------------------------------------------------
Fatal error:
Incorrect thermostat setup in relative_tstat, ti = -1
------------------------------------------------------

How to resolve this issue? Why the changed parameter gives a fatal error?

I look forward to your response.
Thank you for reading.