Dear LAMMPS users,
I am trying to model Silica crystal at 1000k. The short range interactions ofSi-Si,Si-O and O-O atoms are modeled with Morse potential. The long-range electrostatic interactions are modeled with comb potential.
I wrote the following commands to model these interactions, but the temperature of the system from the NVT simulations is unreasonably high at the first step (over 3000K).
units metal
atom_style charge
boundary p p p
read_data SiO2.data
mass 1 28.0855
mass 2 15.9994
pair_style hybrid/overlay morse 9.0 comb
pair_coeff 1 1 morse 0.007695 2.0446 3.7598
pair_coeff 1 2 morse 1.99597 2.6518 1.628
pair_coeff 2 2 morse 0.23272 1.3731 3.791
pair_coeff * * comb ffield.comb Si O
neighbor 0.3 bin
neigh_modify delay 5
compute pe1 all pe/atom
compute ke1 all ke/atom
compute F_temp all temp
thermo 100
thermo_modify temp F_temp lost ignore norm yes
timestep 0.001
velocity all create 1000 213789
fix 1 all nvt temp 1000 1000 0.05 #iso 0.0 0.0 0.5 drag 0.2
fix 2 all qeq/comb 10 0.001
dump 1 all custom 1000 SiO2-melt.lammpstrj id type x y z c_ke1 c_pe1
restart 10000 SiO2.*.inp
run 50000
I wonder how to correct it?
Looking forward to your reply.
Liu Shuhui
Nanchang University