[gmx-users] Error in simulated annealing

[Seera Suryanarayana]

Dear gromacs users,
I wanted to do simulated annealing and I set up the .mdp file as follow...

title           = OPLS 4qam MD simulation
define          = -DPOSRES      ; position restrain the protein
; Run parameters
integrator      = md            ; leap-frog integrator
nsteps          = 50000000      ; 2 * 50000000 = 500000 ps (100 ns)
dt                  = 0.002             ; 2 fs
; Output control
nstxout                 = 50000         ; save coordinates every 100.0 ps
nstvout                 = 50000         ; save velocities every 100.0 ps
nstenergy               = 50000         ; save energies every 100.0 ps
nstlog                  = 50000         ; update log file every 100.0 ps
nstxout-compressed  = 50000      ; save compressed coordinates every 100.0
ps
                                ; nstxout-compressed replaces nstxtcout
compressed-x-grps   = System    ; replaces xtc-grps
; Bond parameters
continuation            = yes           ; Restarting after NPT
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
scheme
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 on
pcoupl                  = Parrinello-Rahman         ; Pressure coupling on
in NPT
pcoupltype              = isotropic                 ; uniform scaling of
box vectors
tau_p                   = 2.0                       ; time constant, in ps
ref_p                   = 1.0                       ; reference pressure,
in bar
compressibility     = 4.5e-5                ; isothermal compressibility of
water, bar^-1
refcoord_scaling    = com
; Periodic boundary conditions
pbc             = xyz           ; 3-D PBC
; Dispersion correction
DispCorr        = EnerPres      ; account for cut-off vdW scheme
; Velocity generation
gen_vel         = no            ; Velocity generation is off







*;simulated annealingannealing            = single
periodicannealing-npoints  = 4 3annealing-time    = 0 4000 8000 12000 16000
20000 24000annealing-temp   = 300 310 315 330 320 310 300*
when I executed the mdrun with above .mdp file I got following error.



*Fatal error:First time point for annealing > init_t.  *
Kindly tell me what could be the reason for the error.

Thanks in advance
*,*
Surya
Graduate student
India.