[Octopus-devel] ARPACK

[Umberto De Giovannini]

Hello everybody,

as you probably remember from discussion related to some of my recent
commit I am implementing some exotic complex scaled DFT in octopus.
One of the main problem here is that the Hamiltonian turns out to be
non-Hermitian.
In this case the eigensolves already implemented are unsuited and
something more general is needed.
The choice is narrowed down to either biconjugate gradient or Arnoldi schemes.
I was thinking to implement an Arnoldi solver with ARPACK.
ARPACK has been out for a while now (and pretty much without any
update until recently http://forge.scilab.org/index.php/p/arpack-ng/)
but appears to be kind of a standard for what Arnoldi scheme is
concerned..
However there has been no attempt to use it with octopus.
So here is the question..
Is there a reason why I should not implement it in octopus?
Are there better solutions to my problem?

ciao

Umberto