Hi Steve,

Thank you for your reply. I am still not sure how to do the energy minimization without dynamics. As you suggested, I did the example indent problem in LAMMPS, and only use minimize after each fix command. But I think the results are not correct. The minimization only has one iteration in each step, and the lattice was not affected by the indenter. So that’s why I always use run before the minimize command. The input script is like this:

# 2d indenter simulation

dimension 2

boundary p s p

atom_style atomic

neighbor 0.3 bin

neigh_modify delay 5

# create geometry

lattice hex 0.9

region box block 0 20 0 10 -0.25 0.25

create_box 2 box

create_atoms 1

mass 1 1.0

mass 2 1.0

# LJ potentials

pair_style lj/cut 2.5

pair_coeff * * 1.0 1.0 2.5

# define groups

region 1 block INF INF INF 1.25 INF INF

group lower region 1

group mobile subtract all lower

set lower atom 2

# initial velocities

fix 2 lower setforce 0.0 0.0 0.0

# indenter

fix 4 all indent 1000.0 sphere 10 13 0 5.0

fix 5 all enforce2d

# Run with indent

thermo 1

dump 1 all atom 1 tmp.dump

minimize 1.0e-4 1000 1000

fix 4 all indent 1000.0 sphere 10 12 0 5.0

dump_modify 1 every 1

minimize 1.0e-4 1000 1000

fix 4 all indent 1000.0 sphere 10 11.8 0 5.0

minimize 1.0e-4 1000 1000

fix 4 all indent 1000.0 sphere 10 11.6 0 5.0

minimize 1.0e-4 1000 1000

fix 4 all indent 1000.0 sphere 10 11.4 0 5.0

minimize 1.0e-4 1000 1000

fix 4 all indent 1000.0 sphere 10 11.2 0 5.0

minimize 1.0e-4 1000 1000

fix 4 all indent 1000.0 sphere 10 11.0 0 5.0

minimize 1.0e-4 1000 1000

fix 4 all indent 1000.0 sphere 10 10.8 0 5.0

minimize 1.0e-4 1000 1000

fix 4 all indent 1000.0 sphere 10 10.6 0 5.0

minimize 1.0e-4 1000 1000

fix 4 all indent 1000.0 sphere 10 10.4 0 5.0

minimize 1.0e-4 1000 1000

fix 4 all indent 1000.0 sphere 10 10.2 0 5.0

minimize 1.0e-4 1000 1000

If you think somewhere is wrong, could you give me some suggestions? Thanks a lot!

Yours,

Jie Lian