when I run command : gmx mdrun -deffnm nvt

I get this error:

Fatal error:

There is no domain decomposition for 30 ranks that is compatible with the

given box and a minimum cell size of 0.96125 nm

I also try for mpirun but even i am getting error.

this is nvt.mdp file i have used

title = OPLS Lysozyme NVT equilibration

define = -DPOSRES ; position restrain the protein

; 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 = 1.0 ; short-range electrostatic cutoff (in nm)

rvdw = 1.0 ; 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 = V-rescale ; modified Berendsen thermostat

tc-grps = Protein Non-Protein ; two coupling groups - more accurate

tau_t = 0.1 0.1 ; time constant, in ps

ref_t = 300 300 ; 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 = 300 ; temperature for Maxwell distribution

gen_seed = -1 ; generate a random seed