Dear lammps, I find an error in the lammps software.

Dear lammps, I find an error in the lammps software.
This is Yangyang Gao, from Beijing University of Chemical Technology. During the simulation in the shear field, when we dump the position of atoms, sometimes the information is wrong for the times (ix iy iz) which the atom has passed through a periodic boundary. For example, the information is below for one chain. The times of some atoms (ix) in one chain is 511, while the times of the other atoms in the same chain is -512. Meanwhile, I found that the wrong information is always 511 or -512 for some chains. Could you please help me to check the code? Thank you very much! Looking forward to your reply.
Best reagrds,
Yangyang Gao

ITEM: ATOMS id type x y z ix iy iz

12151 1 162.945 159.804 148.159 511 -1 1
12152 1 163.706 159.202 148.08 511 -1 1
12153 1 163.792 158.207 148.157 511 -1 1
12154 1 164.605 158.246 147.605 511 -1 1
12155 1 164.549 158.51 146.662 511 -1 1
12156 1 164.13 158.294 145.895 511 -1 1
12157 1 164.857 158.889 145.658 511 -1 1
12158 1 165.163 158.052 145.887 511 -1 1
12159 1 165.802 158.053 146.609 511 -1 1
12160 1 133.699 157.786 145.781 -512 -1 1
12161 1 134.574 158.112 145.851 -512 -1 1
12162 1 135.026 158.894 145.766 -512 -1 1
12163 1 135.945 158.564 145.662 -512 -1 1
12164 1 136.933 158.632 145.882 -512 -1 1
12165 1 137.777 158.797 146.319 -512 -1 1
12166 1 138.645 159.232 146.263 -512 -1 1
12167 1 139.385 159.793 146.544 -512 -1 1
12168 1 140.076 160.121 147.118 -512 -1 1
12169 1 141.03 159.932 146.899 -512 -1 1
12170 1 141.465 160.826 146.813 -512 -1 1
12171 1 142.282 160.576 146.472 -512 -1 1
12172 1 143.212 160.697 146.195 -512 -1 1
12173 1 143.804 159.938 146.057 -512 -1 1
12174 1 144.23 159.772 146.861 -512 -1 1
12175 1 145.145 159.986 146.751 -512 -1 1
12176 1 146.135 159.991 146.695 -512 -1 1
12177 1 146.998 160.134 147.125 -512 -1 1
12178 1 147.446 160.719 147.817 -512 -1 1
12179 1 148.246 161.22 148.05 -512 -1 1
12180 1 148.743 162.024 148.33 -512 -1 1

Dear lammps, I find an error in the lammps software.
This is Yangyang Gao, from Beijing University of Chemical Technology. During the simulation in the shear field, when we dump the position of atoms, sometimes the information is wrong for the times (ix iy iz) which the atom has passed through a periodic boundary. For example, the information is below for one chain. The times of some atoms (ix) in one chain is 511, while the times of the other atoms in the same chain is -512. Meanwhile, I found that the wrong information is always 511 or -512 for some chains. Could you please help me to check the code? Thank you very much! Looking forward to your reply.

this is not a bug, but due your image flags are overflowing due to the continued simulation.
there are only 10 bits available to represent image flags by default and that may overflow if atoms pass through the periodic boundaries a lot.

if you change your makefile to compile LAMMPS with the -DLAMMPS_BIGBIG setting, you have 21 bits instead, and this kind of behavior will happen much, much, much later.

axel.