[gmx-users] Fatal error: Not enough ref_t and tau_t values!

[Markus O Kaukonen]

Dear All,

My system is a protein embedded in tip4 water.
oplsaa force field is used.
Trying to mdrun it at NPT.

Question:
When running grompp one gets output:
>Setting particle type to Dummy for dummy atoms
>Walking down the molecule graph to make shake-blocks
>initialising group options...
>processing index file...
>Making dummy/rest group for T-Coupling containing 22354 elements
>Fatal error: Not enough ref_t and tau_t values!

So it seems to me that grompp generates new temperature group
(for dummy atoms of tip4 water?)
but cannot find ref_t and tau_t values.

Tried adding more ref_t and tau_t values in .mdp file but that also causes
fatal error.

Is there a way around?
My .mdp file is below

Terveisin Markus

; OPTIONS FOR WEAK COUPLING ALGORITHMS =
; Temperature coupling   =
tcoupl                   = berendsen
; Groups to couple separately =
tc-grps                  = System
; Time constant (ps) and reference temperature (K) =
tau_t                    = 0.1
ref_t                    = 300
; Pressure coupling      =
Pcoupl                   = berendsen
Pcoupltype               = Isotropic
; Time constant (ps), compressibility (1/bar) and reference P (bar) =
tau_p                    = 1.0
compressibility          = 4.5e-5
ref_p                    = 1.0

; GENERATE VELOCITIES FOR STARTUP RUN =
gen_vel                  = no
gen_temp                 = 340.0
gen_seed                 = 173529

cpp                 =  /lib/cpp
define              =
integrator          =  md
nsteps              =  500000
dt                  =  0.001




; OUTPUT CONTROL OPTIONS
; Output frequency for coords (x), velocities (v) and forces (f)
nstxout                  = 10000
nstvout                  = 100000
nstfout                  = 100000

; Output frequency for energies to log file and energy file
nstlog                   = 1000
nstenergy                = 1000

pbc                      = xyz

ns_type                  = grid
; OPTIONS FOR ELECTROSTATICS AND VDW
; Method for doing electrostatics
coulombtype = PME
vdwtype = Shift
rlist=1.0
rvdw=0.9
rvdw_switch=0.8
rcoulomb = 0.9
fourierspacing           = 0.075
pme_order                = 4
ewald_rtol               = 1e-05
optimize_fft             = yes