Hello Users and Experts,
nobody here will be willing to solve problems with an 8 year old version of LAMMPS.
besides, there is too little information here to make any specific statement and what you provide makes no sense. how can a calculation “finish cleanly” when it stops at a different step number that you had asked for? as a computer program, LAMMPS will a) execute exactly what you are asking for (which may not be what you think it is) or b) it will crash, or c) you can run into a bug. it is impossible tell (but most likely) that case a) applies, in case b) there must be some indication (but not necessarily in the log file, but probably in the console output from the batch system) and for c) you have to keep in mind, that there were bugs fixed in LAMMPS in the last 8 years, so before anybody would be willing to have a closer look (to avoid resolving a bug that has already been fixed), the first thing you should try is to check, if the same issue happens with a current version of LAMMPS (you may need to adjust some settings in your input, since LAMMPS is not 100% backward compatible over such a long period).
axel.