For a simulation run I want to relax a LJ copper substrate @ T=0 && p=0 with lateral fixed boundaries and fixed/open boundaries in y-direction. Therefore I intend to use the minimization method. The thermodynamic variables p and T are looking reasonable. But when I visualize the surface particles with the centro symmetric parameter P>10 (threshold can also be lower), the surface is only detected at the upper boundaries and not at the lower boundaries (x,y,z=0).
This is my setup:
boundary mm ms mm
lattice fcc 3.615
region simulationbox_region block 0 55 0 55 0 55
create_box 1 simulationbox_region
mass * 63.55
pair_style lj/cut/opt 7.23
pair_coeff * * 0.4229 2.338
fix nve_fix all nve
dump dump_pos all custom 1 pos/dump.*.gz x y z centro
minimize 1.0e-40 10000 10000
Has anybody an idea, why the centro symmetric parameter doesn’t detect the surface at the lower boundaries? Is this a problem with LAMMPS or maybe a problem with my physical setup?