MEAM potential solid structure

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1

Hello i’m doing a simulation with MEAM potential but i have some problems, for example when i build a video the atoms have a strong movement, even changing temperature until 100 or 10 k, but the total energy and potential energy are stable, for me is not logical, because it’s a simulation of a solid, in this case palladium and the analysis should show a solid, and show me a fluid.
I assumed that was a problem of equilibration but it is not true, the particles never stoped of move, never show me a solid structure, here a example of a input file that i use. Thanks.

units real

boundary f f f

atom_style full

dimension 3

read_data data.pdme4

pair_style meam
pair_coeff * * /home/home/Descargas/lammps-11Nov13/potentials/library.meam Pd /home/home/Descargas/lammps-11Nov13/potentials/Pd2.meam Pd
#pair_coeff 1 1 10.563 2.5158
#pair_coeff 2 2 13.48709 2.4622
dihedral_style none
improper_style none

group paladiorodio id 1

neighbor 4.0 bin
neigh_modify every 1 delay 1 check yes

fix 2 all nvt temp 100.0 100.0 30
fix reflect all wall/reflect xlo EDGE xhi EDGE ylo EDGE yhi EDGE zlo EDGE zhi EDGE

velocity all create 100 432567 dist uniform
compute cna all cna/atom 3.5
compute centro all centro/atom fcc
compute cluster all cluster/atom 4.0
compute coord all coord/atom 3.5
compute ackland all ackland/atom

timestep 1
thermo 5000
thermo_style custom step temp pe etotal ecoul evdwl enthalpy
thermo_modify norm yes

dump video all atom 5000 dump.pdme7-TIF
dump 1 all custom 5000 dump.fcc3 id x y z c_cna c_centro c_cluster c_coord c_ackland

restart 50000000 restart.*.pdme7-TIF

run 50000000

2

Hello i'm doing a simulation with MEAM potential but i have some problems,
for example when i build a video the atoms have a strong movement, even
changing temperature until 100 or 10 k, but the total energy and potential
energy are stable, for me is not logical, because it's a simulation of a
solid, in this case palladium and the analysis should show a solid, and show
me a fluid.
I assumed that was a problem of equilibration but it is not true, the
particles never stoped of move, never show me a solid structure, here a
example of a input file that i use. Thanks.

so what is your question here?

LAMMPS will take whatever input you feed it and follow the
prescription in the code to take that data and compute its trajectory.

if you don't get the trajectory you expect, then either your input
(structure, system description, parameters, model, simulation
parameters) is not correct, or your expectations are wrong. which is
which is usually not possible to tell from a few lines of LAMMPS
input. occasionally, there may be a bug in the LAMMPS code, but before
somebody will have a closer look at that, you have to provide
convincing proof (not just "i don't get what i want"). this is most
unlikely for a simple system like yours.

furthermore, making sure that you set up the simulation the way you
want and have it done correctly, is your job not somebody else's.
learning how to systematically narrow down a problem of a
"misbehaving" simulation is part of the business.

axel.