Dear LAMMPS users,

suppose that the lattice structure of your material is monoclinic such as SiC, SiN and etc. However, you have to do your simulation on a cubic simulation box. For the sake of thism I used the following code, define a cubic region and fill it with atoms as follow:

units metal

atom_style atomic

dimension 3

boundary p p p

#------------Define variable------------------------

variable n equal 10

variable a equal 7.5572

variable b equal 7.5572

variable c equal 2.8852

variable gamma equal “120.0030/180*PI"
variable singamma equal “sin(v_gamma)”
variable cosgamma equal “cos(v_gamma)”
variable bx equal "v_b*v_cosgamma”

variable by equal “v_b

*v_singamma"*

variable prismx equal "v_bv_cosgamma/v_n”

variable prismx equal "v_b

#------------Define Si3N4 lattice------------------------

lattice custom 1 &

a1 a 0.0 0.0 &
a2 {bx} ${by} 0.0 &

a3 0 0.0 $c &

basis 0.1742 0.7678 0.2500 &

basis 0.2322 0.4064 0.2500 &

basis 0.5936 0.8258 0.2500 &

basis 0.8258 0.2322 0.7500 &

basis 0.7678 0.5936 0.7500 &

basis 0.4064 0.1742 0.7500 &

basis 0.3333 0.6667 0.2500 &

basis 0.6667 0.3333 0.7500 &

basis 0.3302 0.0299 0.2500 &

basis 0.9701 0.3003 0.2500 &

basis 0.6997 0.6698 0.2500 &

basis 0.6698 0.9701 0.7500 &

basis 0.0299 0.6997 0.7500 &

basis 0.3003 0.3302 0.7500 &

orient x 1 0 0 orient y 0 1 0 orient z 0 0 1

#------------------Create SiC nanowire--------------

region zona1 block 0 75 0 75 0 15 units box

create_box 2 zona1

create_atoms 1 box &

basis 1 2 &

basis 2 2 &

basis 3 2 &

basis 4 2 &

basis 5 2 &

basis 6 2 &

basis 7 1 &

basis 8 1 &

basis 9 1 &

basis 10 1 &

basis 11 1 &

basis 12 1 &

basis 13 1 &

basis 14 1 &

write_data SiC.in

So, my problem is that the structure doesn’t look correct for the sake of periodicity. I attached an image of it and circle around the section of the boundary that as I switch on show periodic image in Ovito, it doesn’t look correct. I mean the structure doesn’t look uniform as we go from left of the boundary to the right of it.