43.3 Restart capabilities

DISK,options

As SURF calculations are very demanding it is highly recommended to dump the grid representation of the potential to disk. Two different options are available: (1) dumping to the binary .wfu-file (options SAVE and RESTART) and (2) dumping to an external ASCII-file (options WHERE, DUMP and DISK). Restarts from the binary file are only possible in case that the SURF calculation has been finished. For crashed SURF calculations restarts are feasible from the external ASCII-file.

SAVE=value

Once a permanent file 2 has been declared in the Molpro input (file,2,filename.wfu), by default the potential generated by the SURF program will be dumped to disk. The default record is 5600.2, but this value can be changed by the SAVE command. This allows for running anharmonic frequency calculations in a separate job without an explicit recalculation of the potential.

RESTART=value

Once an entire surface calculation has been completed, the calculation can be restarted from the binary file 2 specified in the MOLPRO input (see the SAVE command) using the RESTART option, e.g. Restart=5600.2. Restarts using the RESTART option will fail for broken SURF calculations, only restarts for finished SURF calculations are possible. Note that, for restarting a calculation, you always need to specify a SURF card. You cannot restart a calculation simply beginning with a VSCF card, although the potential may be completely available on record 5600.2.

WHERE=value

In combination with the keywords DUMP and EXTERN for an external restart file, the keyword WHERE specifies the path for the external ASCII file. Two options are available, WHERE=home and WHERE=scr. As the external files can be huge for SURF calculations, they will be stored on the scratch disk given by the MOLPRO variable $TMPDIR by default.

DUMP=file name

The potential can be dumped into an external ASCII-file which can be used for restarting. Its name must be provided as the argument of the DUMP keyword, e.g. DUMP='formaldehyde.pot'. The ASCII-file provides the interface to other programs and offers the possibility for controlled storage and modification of the computed potentials. Dipole surfaces will also be dumped if available.

EXTERN=file name

In principle, SURF calculations should be restartable at any point of a truncated calculation. However, since only fully converged difference potentials will be stored in the ASCII file (DUMP), this is not the case. As a consequence, SURF calculations can be restarted from dump-files once a batch of surfaces has been dumped. Since the generation of the 2D or 3D surfaces usually requires about 2 to 3 batches, there are about 6-10 restart points for surface calculation including 3D potentials. Restarting from the ASCII dump-file is possible for any type of VMULT calculation. As normal modes and harmonic frequencies will also be read in from the external file, harmonic frequency calculations need not to be repeated for such restarts.