Question

If you want an example using a loop here it is. I'm in a hurry and
I feel a little bit irresponsible posting this because I have not
tested it. (I adapted it from something else.) This example is
probably more complicated than it needs to be. Try it, and if it does
not work, please post a reply.
  If you don't want the temperature to vary linearly, then modify the
formula for variable Ttarget. You will probably want to change the
"Tdamp" parameters ("100" and "2000" in the example below) to be
appropriate for your system.
   Hopefully this gets you started

Cheers

Andrew

  (Comment on Chang Woons suggestion: Remember to use the "unfix"
command after each run if you want to reuse the same fixID. There may
be mistakes with this post too.)

# ------ run section of input script with temp loop -----

# You may want to reduce your timestep with increasing temperature,
# but for now, just use a constant timestep
timestep 1.0

# You can specify all of your dump and thermo commands once
# beforehand, or you can put them in the loop, but remember
# to use "undump" and "dump_modify" each time if you do that.
#dump 1 all custom 20000 traj.lammpstrj id mol type x y z ix iy iz
#thermo_style custom step temp pe etotal press vol
#thermo_modify norm no
#thermo 1000

variable nloop1 loop 601

    label loop1

    # optional: I renamed the "step" variable to "time"
    # I don't remember why. Not important.
    variable time equal step
    variable Ttarget equal \(601\-\(v\_time\)/5000\.0\)     \# This would probably also work:     \# variable Ttarget equal (601-(v_loop1))

    # optional: Have a file containing temperature versus time
    print "timestep = \{time\}, Ttarget = {Ttarget}" file Ttarget_vs_time.dat

    # Tstart Tstop Tdamp

    fix fxnvt all nvt \{Ttarget\} {Ttarget} 100.0

    # If you use Langevin dynamics, try this way instead:
    # http://lammps.sandia.gov/doc/fix_langevin.html
    # Tstart Tstop tdamp randomseed
    #fix fxlan all langevin \{Ttarget\} {Ttarget} 2000.0 ${time}
    #fix fxnve all nve

    run 5000

    unfix fxnvt

    #If you use langevin dynamics, do this instead:
    # unfix fxlan
    # unfix fxnve

    next nloop1
    jump SELF loop1

Thanks dear all
I think that understand how do it,
regards

If you want an example using a loop here it is. I’m in a hurry and
I feel a little bit irresponsible posting this because I have not
tested it. (I adapted it from something else.) This example is
probably more complicated than it needs to be. Try it, and if it does
not work, please post a reply.
If you don’t want the temperature to vary linearly, then modify the
formula for variable Ttarget. You will probably want to change the
“Tdamp” parameters (“100” and “2000” in the example below) to be
appropriate for your system.
Hopefully this gets you started

Cheers

Andrew

(Comment on Chang Woons suggestion: Remember to use the “unfix”
command after each run if you want to reuse the same fixID. There may
be mistakes with this post too.)

------ run section of input script with temp loop -----

You may want to reduce your timestep with increasing temperature,

but for now, just use a constant timestep

timestep 1.0

You can specify all of your dump and thermo commands once

beforehand, or you can put them in the loop, but remember

to use “undump” and “dump_modify” each time if you do that.

#dump 1 all custom 20000 traj.lammpstrj id mol type x y z ix iy iz
#thermo_style custom step temp pe etotal press vol
#thermo_modify norm no
#thermo 1000

variable nloop1 loop 601

label loop1

optional: I renamed the “step” variable to “time”

I don’t remember why. Not important.

variable time equal step
variable Ttarget equal $(601-(v_time)/5000.0)

This would probably also work:

variable Ttarget equal $(601-(v_loop1))

optional: Have a file containing temperature versus time

print “timestep = {time}, Ttarget = {Ttarget}” file Ttarget_vs_time.dat

Tstart Tstop Tdamp

fix fxnvt all nvt {Ttarget} {Ttarget} 100.0

If you use Langevin dynamics, try this way instead:

http://lammps.sandia.gov/doc/fix_langevin.html

Tstart Tstop tdamp randomseed

#fix fxlan all langevin {Ttarget} {Ttarget} 2000.0 ${time}
#fix fxnve all nve

run 5000

unfix fxnvt

#If you use langevin dynamics, do this instead:

unfix fxlan

unfix fxnve

next nloop1
jump SELF loop1