Eigensolvers

[PaulWAyers]

Not sure if it matters, but we are looking at large-scale eigensolvers together for @Ali-Tehrani problems. They are a bit different from what you are doing in PyCI (and EOM/ERPA) but here is what we've found (emphasizing GPU and hybrid codes).

We are starting with PySparse, but these may be better sources (just harder).

Jacobi-davidson works well with GPUs too. But it takes more memory than Lanczos.

Fortran and C codes

SLEPc seems to have a Python interface. As part of PETSC a GPU implemention should be coming (if it isn't there already).

PHIST looks like a really cool (and modern!) GPU code.