Equilibration a surface at a temperature of 10 Kelvin

dear lammps users,

I want to equilibrate a surface containing 662 particles at a temperature of10 Kelvin, Using the following input:

dimension 3
units real
boundary p p p
atom_style full
neighbor 2 bin
neigh_modify delay 0 every 1 check yes

lattice fcc 3
region box block -1 31 -1 31 -10 31 units box
create_box 1 box

region substrate block 0 31 0 31 0 3 units box
create_atoms 1 region substrate

pair_style lj/cut 2.5

pair_coeff * * 1.376517 2.8
mass * 60.1

fix 2 all langevin 10 10 100 587283
fix 3 all nve

thermo 100
thermo_style custom atoms step temp etotal press
timestep 1

dump 1 all xyz 1000 dumpsi.xyz

run 100000

But the surface is distorted. I have added the initial configuration of the system and the next configuration.
Someone can help me with this error?

1.png

2.jpg

This meant the potential is not suitable for describing the surface.

Ray