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[lammps-users] Problem with defining correct cubic simulation box

# [lammps-users] Problem with defining correct cubic simulation box

 From: "Khourshaei Shar, Ali" Date: Fri, 20 Apr 2018 22:49:23 +0000

 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_b*v_cosgamma/v_n" #------------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.

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