Dear lammps users,

In the lattice part of the command I find the commands for generating Wurtzite crystal, and the generated crystal is like this

I find from the wikipedia that in Wurtzite crystal each of the two individual atom types forms a sublattices which is HCP-type (short for “hexagonal close-pack”), The distance between the lower layer of yellow balls and the bottom is 3/8c(the distance between the two layers of yellow balls is 1/2c),like this

I find that lammps-Wurtzite.png and Wurtzite.png are not the same crystal structure, so I write my own commands:

variable a equal 4.340330

variable b equal $a*sqrt(3.0)
variable c equal $a*sqrt(8.0/3.0)

variable 1_3 equal 1.0/3.0

variable 2_3 equal 2.0/3.0

variable 1_6 equal 1.0/6.0

variable 5_6 equal 5.0/6.0

variable 1_12 equal 1.0/12.0

variable 5_12 equal 5.0/12.0

lattice custom 1.0 &

a1 $a 0.0 0.0 &

a2 0.0 $b 0.0 &

a3 0.0 0.0 c &
basis 0.0 0.0 0.0 &
basis 0.5 0.5 0.0 &
basis 0.0 {2_3} 0.5 &

basis 0.5 {1_6} 0.5 &
basis 0.0 0.0 0.375 &
basis 0.5 0.5 0.375 &
basis 0.0 {2_3} 0.875 &

basis 0.5 ${1_6} 0.875

region myreg block -0.6 1.6 0 1.2 0 1.1

create_box 2 myreg

create_atoms 2 box &

basis 1 1 &

basis 2 1 &

basis 3 1 &

basis 4 1 &

basis 5 2 &

basis 6 2 &

basis 7 2 &

basis 8 2

the generated crystal is like this

Have anyone found the same problem? Is my commands right? or do I misunderstand the Wurtzite crystal structure?

Any discussion would be appreciated.

Best regards,

Michelle