Fix atom/swap - atom charges

Dear Lammps Users:

I am using the fix atom/swap command to swap Pt and Au atoms from time to time.

I assigned the same charge (0.0) for both Pt (type 2) and Au (type 1) atoms at the beginning.

When I write out the output data (id mol type q x y z vx vy vz), I see that Pt atoms have different charge within themselves ( 0 and 1.79769e+308)

For example

ITEM: ATOMS id mol type q x y z vx vy vz

108 1 2 1.79769e+308 12.7449 11.0262 7.96111 -0.574294 0.533616 -2.34751
109 1 2 1.79769e+308 10.3897 10.1799 8.03227 -4.18462 -0.821569 -0.280544
110 1 1 0 9.40457 11.6813 15.9241 -1.56762 -0.498689 -2.22995
111 1 1 0 9.57487 9.06232 15.9039 -1.28628 -0.801723 -0.0989734
112 1 1 0 5.78286 11.3469 12.3917 -1.2633 3.07167 -1.09409
113 1 2 1.79769e+308 8.26107 10.3445 10.7452 0.0350916 -3.07806 -1.80724
114 1 1 0 12.9521 11.5441 12.4626 4.30217 2.5174 1.61667
115 1 1 0 15.473 9.62439 8.16657 -0.555348 -0.226016 -1.14661
116 1 1 0 7.692 13.7084 15.9559 0.398798 -0.215037 -0.31331
117 1 1 0 12.0989 9.86795 15.324 0.394699 1.99024 -1.81806
118 1 2 0 8.8011 12.4296 8.75717 1.55424 2.08783 1.10326
119 1 1 0 16.8601 9.2923 14.2775 -2.5053 -3.25283 1.97384
120 1 2 0 11.1362 13.0917 7.87464 -0.27749 -0.872185 0.901209
121 1 2 0 12.6091 12.4533 16.7869 2.84071 -0.712624 0.620648

Could you please explain to me why Pt atoms are assigned with different charges like this?

Thank you.

Sincerely,

Anh

Dear Lammps Users:

I am using the fix atom/swap command to swap Pt and Au atoms from time to
time.

I assigned the same charge (0.0) for both Pt (type 2) and Au (type 1)
atoms at the beginning.

When I write out the output data (id mol type q x y z vx vy vz), I see
that Pt atoms have different charge within themselves ( 0 and
1.79769e+308)

For example

ITEM: ATOMS id mol type q x y z vx vy vz
....
108 1 2 *1.79769e+308* 12.7449 11.0262 7.96111 -0.574294 0.533616
-2.34751
109 1 2 *1.79769e+308* 10.3897 10.1799 8.03227 -4.18462 -0.821569
-0.280544
110 1 1 0 9.40457 11.6813 15.9241 -1.56762 -0.498689 -2.22995
111 1 1 0 9.57487 9.06232 15.9039 -1.28628 -0.801723 -0.0989734
112 1 1 0 5.78286 11.3469 12.3917 -1.2633 3.07167 -1.09409
113 1 2 *1.79769e+308* 8.26107 10.3445 10.7452 0.0350916 -3.07806
-1.80724
114 1 1 0 12.9521 11.5441 12.4626 4.30217 2.5174 1.61667
115 1 1 0 15.473 9.62439 8.16657 -0.555348 -0.226016 -1.14661
116 1 1 0 7.692 13.7084 15.9559 0.398798 -0.215037 -0.31331
117 1 1 0 12.0989 9.86795 15.324 0.394699 1.99024 -1.81806
118 1 2 *0* 8.8011 12.4296 8.75717 1.55424 2.08783 1.10326
119 1 1 0 16.8601 9.2923 14.2775 -2.5053 -3.25283 1.97384
120 1 2 *0* 11.1362 13.0917 7.87464 -0.27749 -0.872185 0.901209
121 1 2 *0* 12.6091 12.4533 16.7869 2.84071 -0.712624 0.620648

Could you please explain to me why Pt atoms are assigned with different
charges like this?

​there is not enough information here to make any specific suggestion.

axel​

Dear Axel:

Thank you for your reply.

Here is my input script.

units metal
atom_style full
dimension 3
boundary p p p
read_data datafile.dat
pair_style eam/alloy
pair_coeff * * potential.set Au Pt
neighbor 2.0 bin
neigh_modify every 1 delay 2 check yes
velocity all create 1223.0 345678
fix 1 all nve
fix 2 all atom/swap 200 10000 98765 1223.0 types 1 2
thermo_style custom step pe ke temp press etotal f_2[1] f_2[2]
thermo 200
dump 1 all custom 200 output1223.data id mol type q x y z vx vy vz
dump_modify 1 sort id
restart 10000 restart.*.1223
run 10000

And here is the information in the datafile

Pt-Au

147 atoms
0 bonds
0 angles
0 dihedrals
0 impropers

2 atom types
0 bond types
0 angle types
0 dihedral types
0 improper types

0.0000 24.0000 xlo xhi
0.0000 24.0000 ylo yhi
0.0000 24.0000 zlo zhi

Masses

1 1.0
2 2.0

Charges of Pt and Au atoms are 0.0 at the beginning.

Could you please give some comments about why Pt atoms are assigned with different charges ( 0 and 1.79769e+308)?

Thanks.

Sincerely,

Anh

This is still not sufficient.
The data file is incomplete.
Also I did not see the most important information : which version of lammps are you using, on what kind of platform and, whether in parallel or not.

Axel