[gmx-users] Fatal error: Invalid T coupling input: 0 groups, 1 ref-t values and 1 tau-t values

[Mark Abraham]

Hi,

You need to specify a group, eg System. That this is not the default
behavior protects you from making a typo and accidentally coupling the
whole system when it was not your intent.

Mark

On Thu, Jul 12, 2018, 17:24 Gonzalez Fernandez, Cristina <
cristina.gonzalezfdez at unican.es> wrote:

> Dear Gromacs users,
>
> I am trying to perform a NVT equilibration. However, I obtain this error:
>
> Fatal error:
> Invalid T coupling input: 0 groups, 1 ref-t values and 1 tau-t values
>
> I don't understand the problem because I don't have defined any group,  I
> am indicating the ref-t and tau-t for the whole system.
>
> My .mdp file is:
>
> define          = -DPOSRES      ; position restrain the lipid
>
> ; Run parameters
> integrator      = md            ; leap-frog integrator
> nsteps          = 50000         ; 2 * 50000 = 100 ps
> dt                 = 0.002             ; 2 fs
>
> ; Output control
> nstxout         = 500           ; save coordinates every 1.0 ps
> nstvout         = 500           ; save velocities every 1.0 ps
> nstenergy       = 500           ; save energies every 1.0 ps
> nstlog          = 500           ; update log file every 1.0 ps
>
> ; Bond parameters
> continuation            = no            ; first dynamics run
> constraint_algorithm    = lincs     ; holonomic constraints
> constraints                 = all-bonds ; all bonds (even heavy atom-H
> bonds) constrained
> lincs_iter                  = 1             ; accuracy of LINCS
> lincs_order                 = 4             ; also related to accuracy
>
> ; Neighborsearching
> cutoff-scheme   = Verlet
> ns_type             = grid              ; search neighboring grid cells
> nstlist             = 10                ; 20 fs, largely irrelevant with
> Verlet
> rcoulomb            = 1.2               ; short-range electrostatic cutoff
> (in nm)
> rvdw                = 1.2               ; short-range van der Waals cutoff
> (in nm)
>
> ; Electrostatics
> coulombtype         = PME       ; Particle Mesh Ewald for long-range
> electrostatics
> pme_order           = 4         ; cubic interpolation
> fourierspacing  = 0.16  ; grid spacing for FFT
>
> ; Temperature coupling is on
> tcoupl          = nose-hoover          ; nose-hoover thermostat
> tau_t           = 0.1                ; time constant, in ps
> ref_t           = 298                ; reference temperature, one for each
> group, in K
>
> ; Pressure coupling is off
> pcoupl          = no            ; no pressure coupling in NVT
>
> ; Periodic boundary conditions
> pbc             = xyz               ; 3-D PBC
>
> ; Dispersion correction
> DispCorr        = EnerPres      ; account for cut-off vdW scheme
>
> ; Velocity generation
> gen_vel         = yes           ; assign velocities from Maxwell
> distribution
> gen_temp        = 298           ; temperature for Maxwell distribution
> gen_seed        = -1            ; generate a random seed
>
>
> Could anyone help me?
>
> Thank you in advance,
> C.
>
> --
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