Dear LAMMPS users,
Hello.
I have tried to run the simulation with TIP4P2005 water model.
After several trial and error, I can run the simulation successfully without error or warning.
The shake works well, which make the bond length and bond angle of TIP4p water molecules constant.
PPPM/tip4p also seems to work fine and temperature is well maintained.
But the problem is that the water molecules don’t move.
When I look into the log file and thermo data, those have same values for each step.
Even though temperature of system is increased to 350K, the result is same.
I can’t find where the problem exist.
Is there any fault in my input data or input script?
(please find the attached files).
Thank you very much.
Best regards,
Sehun Joo
====================================================================
Define variables
====================================================================
input data file
variable lmp_data string data.water
temperature and pressure
variable T equal 350
variable p equal 3/0.101325
interactions / rcut
variable rcut equal 12
number of steps / timestep
variable nstep equal “10000000”
variable dt equal 2
output
variable freq_thermo equal “100” # thermo output every
variable freq_frame equal “10000” # frame output every
variable freq_snap equal “v_nstep/10” # xyz output every for safety (rerun)
====================================================================
Initialization
====================================================================
units real
boundary p p p
dimension 3
atom_style full
====================================================================
Force Field
====================================================================
read_data ${lmp_data}
#replicate 5 5 5
1 WH
2 WO
mass 1 1.008
mass 2 15.9994
pair_style lj/cut/tip4p/long 2 1 1 1 0.1546 ${rcut}
pair_modify mix arithmetic
pair_coeff 1 1 0 0
pair_coeff 1 2 0 0
pair_coeff 2 2 0.1852 3.1589
1 WH-WO
bond_style harmonic
bond_coeff 1 900 0.9572
5 WH-WO-WH (fix)
angle_style harmonic
angle_coeff 1 124 104.52
Coulomb interaction
kspace_style pppm/tip4p 1.0e-4
#special_bonds lj/coul 0.0 0.0 0.0
group o type 2
group water type 1 2
====================================================================
Constraints
====================================================================
fix fixtip4p all shake 0.0001 20 10 b 1 a 1
====================================================================
1. RELAX / NVT
====================================================================
velocity all create $T 87654 dist gaussian mom yes rot yes
fix thermostat all temp/berendsen {T} {T} 100.0
#fix barostat all press/berendsen aniso {p} {p} 1000.0
thermo ${freq_thermo}
thermo_style custom step cpuremain temp press etotal pe ke epair ecoul evdwl ebond eangle edihed
thermo_modify flush yes
dump dtrj all custom 100 ${lmp_data}.lammpstrj id type x y z mol
dump dsnap all custom {freq_frame} {lmp_data}_*.lammpstrj id type x y z mol
dump dxyz all xyz 100 ${lmp_data}_*.xyz
dump_modify dxyz element H O
reset_timestep 0
timestep ${dt}
run 50000
undump dtrj
undump dsnap
write_restart restart.RELAX01
print “01.RELAX done”
data.water (30.7 KB)
in.water (2.8 KB)