# Initialization
units real
boundary p p p
dimension 3
atom_style molecular

read_data UA-beads.data

# Force field
bond_style harmonic
bond_coeff 1 100 1.00
angle_style harmonic
angle_coeff 1 60.00 100.00
angle_coeff 2 45.00 100.00
dihedral_style nharmonic
dihedral_coeff 1 4 0.9 1.0 0.4 -3.00
dihedral_coeff 2 4 0.9 1.0 0.4 -3.00
improper_style harmonic
improper_coeff 1 120 60.0
pair_style lj/cut 12.0
pair_coeff 1 1 0.02 4.00
pair_coeff 2 2 0.09 3.00
pair_coeff 3 3 0.20 3.00
pair_coeff 4 4 2.00 4.00

# enlarge the simulation box in Z direction
change_box all z final -30 100 

# # Add walls in Z direction
# region hiwall block INF INF INF INF 90 100
# region lowall block INF INF INF INF -30 -20
# lattice fcc 2.925 
# create_atoms 4 region hiwall ratio 1 4353
# create_atoms 4 region lowall ratio 1 3542

write_data enlarged_box.data nocoeff