General Driver Updates

[mrossinek]

What is the expected enhancement?

#147 also suggest some general improvements to the drivers. The implementation of these is tracked by this issue:

• relocate qiskit_nature.drivers.* into qiskit_nature.drivers.second_quantization.*
• relocate qiskit_nature.transformers.* into qiskit_nature.transformers.second_quantization.*
• check the "file"-based drivers for general improvements:
  • fcidumpd
  • hdf5d
• check the "program"-based drivers for general improvements:
  • pyscfd
  • pyquanted
  • psi4d
  • gaussiand

While performing the checks for general improvments we should also check for the ability of the driver to perform more input validation and update the documentation of all methods.

[mrossinek]

With #173 nearing its merging and #180 following suite shortly after, two major (and the most important) steps of this issue will be addressed soon. None of the other drivers are technically high priority right now because none of them immediately block other implementations planned in the near future.
Nonetheless, all driver codes should be checked in order to determine what kind of updates are possible and to estimate the time such updates would take on a case by case basis. Most drivers are likely to undergo very little changes because besides PySCF all but one other driver are not interfacing another Python-based code, limiting the code complexity which could be updated in a similar style to #180.

[mrossinek]

As part of migrating the new drivers to the property framework (#264) I have checked each open driver for an estimated amount of time required to refactor it. I will summarize below:

Driver	Estimated Time required
pyscf	Done and fully migrated after #264
pyquante	very similar to PySCF, portable in 0.5-1 days
psi4	relies on hdf5 framework (see below)
gaussian (electronic)	relies on gauopen module, mostly Property integration required, (maybe some function reorganization), portable in 0.5-1 days
gaussian (vibrational + log)	relies on GaussianLogResult, portable in 0.5-1 days
fcidump	basically done after #264
hdf5	requires more discussion (#302)

The migration of the remaining drivers will likely not be part of the 0.2.0 release.

[mrossinek]

A quick update on this epic:

• pyquante: handled by PyQuante Driver Update #525
• psi4: handled by PSI4 Driver Update #521
• gaussian: handled by Gaussian driver updates #552
• hdf5: handled by HDF5 Driver Update #550

The goal will be to refactor all drivers thereby decoupling the need for the legacy driver results from all but the HDF5Driver (which should still support loading legacy .hdf5 files) and the properties which allow conversion from legacy driver results.
However, decoupling everything else should allow to move the deprecated legacy types away from the public API location into the backend, effectively hiding them from the user.

[pbark]

I am moving this epic back to product backlog until we have completed the hdf5 and the rest of the drivers updates.