Exporting binary alloys as .cfg files

LAMMPS LAMMPS General Discussion
,
1

Dear all,
I’m exporting a trajectory as a series of .cfg snapshot.
originally I did
dump traj all cfg 100 dump.config..cfg mass type xs ys zs
then
dump traj all cfg 100 dump.config..cfg mass type xs ys zs id type
in the first case it writes all the atoms as carbon
in the second case it writes the atom type as carbon then adds a second entry with the types I defined in the lammps script (1 and 2)

excerpt from the file
Number of particles = 4000
A = 1 Angstrom (basic length-scale)
H0(1,1) = 38 A
H0(1,2) = 0 A
H0(1,3) = 0 A
H0(2,1) = 0 A
H0(2,2) = 38 A
H0(2,3) = 0 A
H0(3,1) = 0 A
H0(3,2) = 0 A
H0(3,3) = 38 A
.NO_VELOCITY.
entry_count = 5
auxiliary[0] = id
auxiliary[1] = type
100.000000
C
0 0 0 1 2
100.000000
C
0 0 0.1 401 1
100.000000

do cfg file need to have actual periodic table elements to distinguish the types?
and default to carbon otherwise?
Thank you,
Mattia

by the way, I was trying to alias the types with the labelmap command but the command is not recognized as existing

2

This is documented behavior. From the dump command docs:

Note that you will typically want to use the dump_modify element command with CFG-formatted files, to associate element names with atom types, so that AtomEye can render atoms appropriately.

Basically, LAMMPS has no concept of elements. It identifies atom settings and force field parameters uniquely with their numeric type. The atom label is merely for visualization / convenience purposes.

3

I see, thanks

4

FWIW, the “labelmap” command is working in the other direction, i.e. you can enter types in the input with labels instead of numbers and then they are internally converted to the corresponding numbers. Once the mapping exists, it may be used the other way through variables. As the documentation for labelmap indicates, this is a very recent addition to LAMMPS and requires that you have version 15 September 2022 or later.
As the documentation indicates, this command is a recent addtion.