Dear @Julia-h2o,

Thank you for your question. You are right that there are many keywords and it is not easy to orient yourself. This is a correct sequence:

EXTERNAL
FREQCALC
RESTART
PREOPTGEOM
FULLOPTG
ENDOPT
INTENS
DIELTENS
5.333073    0.0000     0.0000
0.00000     5.333073   0.0000
0.00000     0.000000   5.333073      
IRSPEC
ENDIR
INTRAMAN                                         
INTCPHF                                               
ENDCPHF
RAMSPEC
ENDRAM
ENDFREQ
END

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.

Dear @Lukas-jd,

Indeed, the PDIDE option is not supported. You can refer to pages 183-184 of the Manual for keywords available from the 2c-SCF solution in the PROPERTIES module.