Restarting calculations

Restarting geometry optimizations

To restart a geometry optimization job that crashed unexpectedly or ran out of iterations, it is easiest to simply take the last set of coordinates and start a new calculation from there. The last set of coordinates can be taken from the outputfile (search for "CARTESIAN COORDINATES" from the bottom) or alternatively from the jobname.xyz file. In some cases you may also want to read in the old orbitals (usually not worth it for optimizations), remember then that you have to use the MOREAD and %moinp keywords for that (see below) as the Autostart feature (automatic reading of old orbitals from an old GBW file) is not active for geometry optimizations.

Restarting single-point calculations

If it is a single-point calculation, note that usually only the SCF-part is restartable (not the post-HF job, or molecular property or spectroscopy job) as well as the numerical frequency job. The Autostart feature of ORCA is the default (use NoAutostart keyword in case you want to turn it off) and a job with inputfile name jobname.inp will automatically search for a GBW file named jobname.gbw (in the same directory as the inputfile; if on a cluster check also that the GBW file gets copied to the scratch space) and will attempt to read in the old orbitals and continue the SCF from there. Alternatively, using the MOREAD and %moinp keywords allows you to manually specify where to read the orbitals from. Note that the GBW file can not have the same basic name as the inputfile in that case (ORCA will fail).

! MORead
%moinp "jobname2.gbw"
# Note that if jobname2.gbw is the gbw file you read in then jobname2.inp can not be the name of the inputfile.
*xyz 0 1
coordinates
*

If the gbw file is from an older ORCA version you may need to use the Rescue keyword to force the newer ORCA version to read the older orbitals (may not always work).

! MORead Rescue
%moinp "jobname2.gbw"
*xyz 0 1
coordinates
*

The Rescue keyword is also necessary in the case of restarting the SCF after a calculation where ORCA left out very low eigenvalues in the overlap matrix (<1e-8 by default). If the keyword is not used, the SCF may explode.

Restarting numerical frequency calculations

Restarting numerical frequency calculations can also be done. One needs to make sure that the .hess files from the previous calculation are present.

Note that if you use a job-submit script on a cluster to make sure that the .hess files are copied to the local scratch directory on the node where the calculation is carried out.

!

%freq
restart true
end

Analytical frequency jobs are not restartable.