[lammps-users] Illegal fix press/berendsen command

Hi:

I am trying to compute the energy of a cubic ZrO2 single crystal under NPT
conditions. I used the press/berendsen command according to the following
script:

units metal
atom_style charge
atom_modify map array
neighbor 0.3 bin
neigh_modify delay 0 every 20 check no
boundary p p p

lattice custom 5.129 orient x 1 0 0 orient y 0 1 0 orient z 0 0 1 &
    basis 0.0 0.0 0.0 basis 0.25 0.25 0.25 &
    basis 0.75 0.75 0.25 basis 0.75 0.25 0.75 basis 0.25 0.75 0.75 &
    basis 0.25 0.25 0.75 basis 0.75 0.75 0.75 basis 0.25 0.75 0.25 &
    basis 0.75 0.25 0.25 basis 0.0 0.5 0.5 basis 0.5 0.0 0.5 &
    basis 0.5 0.5 0.0
region caja block -2 2 -2 2 -5 5
create_box 2 caja

region grano block -2 1.9 -2 1.9 -5 4.9
create_atoms 2 region grano basis 1 1 basis 10 1 basis 11 1 basis 12 1 &
    basis 2 2 basis 3 2 basis 4 2 basis 5 2 basis 6 2 basis 7 2 &
    basis 8 2 basis 9 2

group zirconium type 1
group oxygen type 2

mass 1 91.22
mass 2 15.99
set group zirconium charge 4
set group oxygen charge -2
velocity all create 900.0 87287 mom no dist gaussian

pair_style buck/coul/long 4.0 10.0
pair_modify shift yes
pair_coeff 1 1 0.0 10.0 0.0
pair_coeff 2 2 9547.96 0.2192 32.0 # Minervini
pair_coeff 1 2 1502.11 0.3477 5.1 # Idem
kspace_style ewald 1.0e-4

minimize 1.0e-6 0.0 5000 10000
write_restart restart.bulk

fix 1 all temp/berendsen 900.0 900.0 0.1
fix 2 all press/berendsen iso 3000.0 3000.0 10.0
fix 3 all nve

dump 1 all atom 1000 dump.bulk.900_K
thermo_style custom step temp ke pe etotal press vol
thermo_modify lost warn norm yes

thermo 1000

run 200000

The output screen is as follows:

LAMMPS (15 Jan 2010)
Lattice spacing in x,y,z = 5.129 5.129 5.129
Created orthogonal box = (-10.258 -10.258 -25.645) to (10.258 10.258 25.645)
  1 by 1 by 2 processor grid
Created 1920 atoms
640 atoms in group zirconium
1280 atoms in group oxygen
  640 settings made for charge
  1280 settings made for charge
Ewald initialization ...
  G vector = 0.273155
  vectors: actual 1d max = 845 13 9841
Memory usage per processor = 16.8243 Mbytes
Step Temp E_pair E_mol TotEng Press
       0 900 -71133.646 0 -70910.401 -39394.079
       1 900 -71133.646 0 -70910.401 -39394.079
Loop time of 0.0927451 on 2 procs for 1 steps with 1920 atoms

Minimization stats:
  Stopping criterion = energy tolerance
  Energy initial, next-to-last, final =
         -71133.646389 -71133.646389 -71133.646389
  Force two-norm initial, final = 5.35275e-12 6.87414e-10
  Force max component initial, final = 3.82028e-13 4.84093e-11
  Final line search alpha, max atom move = 1 4.84093e-11
  Iterations, force evaluations = 1 1

Pair time (\) = 0\.0608647 \(65\.6257\) Kspce time \() = 0.030176 (32.5365)
Neigh time (\) = 0 \(0\) Comm time \() = 0.00145247 (1.56609)
Outpt time (\) = 0 \(0\) Other time \() = 0.000251991 (0.271703)

Nlocal: 960 ave 960 max 960 min
Histogram: 2 0 0 0 0 0 0 0 0 0
Nghost: 6394 ave 6394 max 6394 min
Histogram: 2 0 0 0 0 0 0 0 0 0
Neighs: 193920 ave 197566 max 190274 min
Histogram: 1 0 0 0 0 0 0 0 0 1

Total # of neighbors = 387840
Ave neighs/atom = 202
Neighbor list builds = 0
Dangerous builds = 0
ERROR: Illegal fix press/berendsen command

I cannot understand what is the problem with the fix press/berendsen
command. Any help?

Thanks in advance!

Juan J. Meléndez Martí­nez
Profesor Titular de Universidad
Departamento de Fí­sica
Universidad de Extremadura
Avda. de Elvas, s/n 06006 Badajoz (España)
Tfno.: 924 28 96 55
Fax: 924 28 96 51
e-mail: [email protected]

This line:

fix 2 all press/berendsen iso 3000.0 3000.0 10.0

is the syntax for the command in the current, fully patched
version of the code. You are using an older version.
If you read the doc pages in the version you have (rather than
from the WWW), it will explain the older syntax. Or just
upgrade to the most current version.

Steve

2010/4/23 Juan J. Meléndez Martí­nez <[email protected]>: