Dear all,
I am experimenting with the COMB3 potential to model a system of Zn/O/H and possibly Ti. I started a simulation with <3000 atoms, and it seems to be running well expect for the fact that it is too slow. When I try simulating the system with Reax/C (which also has the parameters for Zn/O/H) speed up is around ~5-10 times of the COMB3. I am wondering if I am doing anything wrong.
I am using lammps-31Mar17 on NERSC resources, and the code is available as a module.
Here is my input file, and for the qeq/reax I used 1E-6 as the convergence criterion.
units metal
atom_style charge
boundary p p p
read_data data.in
mass 1 1.00
mass 2 16.0
mass 3 65.4
pair_style comb3 polar_off
pair_coeff * * ffield.comb3 H O Zn
fix qeq all qeq/comb 10 1E-3 # tried to speed up, was 1 1E-3
neighbor 2.0 bin
neigh_modify every 1 delay 0 check yes
dump 1 all custom 2000 nano.lammpstrj element x y z
dump_modify 1 sort id element H O Zn append yes
timestep 2E-4
thermo_style custom step time temp press vol pe etotal enthalpy
thermo_modify flush yes
thermo 2000
# equilibrate charge first; minimization hangs indefinitely otherwise
fix 1 all nvt temp 300.0 300.0 0.1
thermo 1
run 1
fix 2 all qeq/comb 1 0.003 file fq.out
run 5
# minimize
unfix 1
fix 1 all box/relax aniso 0.0 vmax 0.0002
minimize 1.0E-8 1.0E-10 10000 100000
write_data data.in
unfix 1
displace_atoms all random 0.08 0.08 0.08 328
fix nvt all nvt temp 300.0 300.0 20
run 1000000
Best,
Sencer