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52.5 Restart capabilities


As SURF calculations are very demanding it is highly recommended to dump the grid representation of the potential to disk. This allows for convenient restarts for subsequent vibrational structure calculations. In contrast to previous Molpro releases, the current version supports only restarts from external ASCII-files - due to many new options. Note, that restarts can also be performed for incomplete potentials. An open-access database of high-level potential files is available at http:// Potential files have their own version number and start with version 3.0 for the current Molpro release. Older potential file versions may not support the full capabilities of the current Molpro release.

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 and polarizability 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 (see also the keywords BATCH3D and BATCH4D of the SURF program). Restarting from the ASCII dump-file is possible for any type of VMULT calculation. Harmonic frequencies should not be recalculated for restarts.
Once a complete surface has been generated, a record can be specified, where to dump the potential in the temporary binary files. Once this keyword is not provided explicitly, the potential will be dumped in record 5600.2

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