Thank you so much for your advice. I actually want to test the stability of the BCN, so I followed your suggestion to use 3 dimension. And I also noticed that reaxff potential can only use for the system that the dimension bigger than 10 angstroms. So that, I make my system as 74*43*50, and still give a 10k initial velocity run 10000step. The time step is 0.1 femtosecond. However, the temperature still goes to over 1000K. I visualized the trajectory, it seems like good ( see the attachment, the first step of system). Could you please help me check that where I got wrong?

Below is my new script.

Sincerely,

Peng

# Heat BCN crystal, ReaxFF test

# Initialization

units real

# variable

variable b equal 4.26

variable a equal $b*sqrt(3.0)

variable 1_3 equal 1.0/3.0

variable 2_3 equal 2.0/3.0

variable 5_6 equal 5.0/6.0

variable 1_6 equal 1.0/6.0

# Setup Box

dimension 3

boundary p p p

atom_style charge

lattice custom 1.0 &

a1 $a 0.0 0.0 &

a2 0.0 $b 0.0 &

a3 0.0 0.0 100.0 &

basis 0.0 0.0 0.0 &

basis ${1_3} 0.0 0.0 &

basis ${2_3} 0.0 0.0 &

basis 0.0 ${2_3} 0.0 &

basis {1_6} {1_6} 0.0 &

basis 0.5 ${1_6} 0.0 &

basis {5_6} {1_6} 0.0 &

basis ${1_6} 0.5 0.0 &

basis 0.5 0.5 0.0 &

basis ${5_6} 0.5 0.0 &

basis {1_3} {2_3} 0.0 &

basis {2_3} {2_3} 0.0 &

region box block 0 10 0 10 -0.25 0.25

create_box 3 box

create_atoms 1 box &

basis 2 2 &

basis 3 3 &

basis 4 2 &

basis 5 3 &

basis 7 2 &

basis 8 3 &

basis 9 2 &

basis 12 3 &

group B type 1

group N type 2

group C type 3

mass 1 10.811

mass 2 14.0067

mass 3 12.0107

# Settings

pair_style reax/c NULL

pair_coeff * * ffield.reax.new B N C

fix 1 all qeq/reax 1 0.0 10.0 1.0e-6 reax/c

compute reax all pair reax/c

timestep 0.1

thermo 1

thermo_style custom step temp press pe ke etotal vol density epair lx ly lz

dump 99 all custom 1 dump.reax.atom id type mass xs ys zs

# Minimization

min_style cg

minimize 1.0e-10 1.0e-10 1000000 1000000

# Heating Stage

velocity all create 10.0 12345 rot yes dist gaussian

fix 2 all nve

run 10000