The JOYCE code alos directly reads all QM data from formatted checkpoint files created by the GAUSSIAN16 package.[20] The formatted checkpoint file (.fchk) can be easily created from the more standard unformatted checkpoint file (.chk) through the utility formchk, available with the GAUSSIAN16 suite of programs.
If a molname.chk unformatted checkpoint file has been created by the GAUSSIAN16 program, this can be thus transformed into a formatted molname file through the command
% > $GAUSS_EXEDIR/formchk molname.chk
where the environment variable $GAUSS_EXEDIR should have been previously defined installing GAUSSIAN16 .