Dear @Julia-h2o,
We had a look at your files. We could not find any error at the end of 4br3clph.out This calculation was regular till the point where the file ends. Is it possible that you reached a wallclock limit on your cluster?
Our suggestion for this kind of heavy calculations is to:
run a OPTGEOM calculation to get the optimized structure;
Starting from the optimized structure run a ELASTCON calculation (without PREOPTGEOM).
Let us know how it goes.