LAMMPS WWW Site - LAMMPS Documentation - LAMMPS Mailing List Archives
[lammps-users] COMB3 too slow (compared to Reax/C)
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[lammps-users] COMB3 too slow (compared to Reax/C)

From: Sencer Selcuk <sselcuk@...1683...>
Date: Thu, 30 Nov 2017 14:04:02 -0500

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

		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
		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