[Q-e-developers] Diagonalization method as input flag in ph.x

[William Parker]

Dear developers,

Using conjugate gradiate diagonalization in ph.x has come up a few times in the mailing list (http://www.democritos.it/pipermail/pw_forum/2012-January/022948.html for one).  I modified my ph.x to compare it and Davidson on my test cases, and a colleague of mine says that on a few systems he's had to switch to conjugate gradient to get convergence.  Is there any reason not to have it set as an input flag (default to 'david' but optional 'cg') like in pw.x?  If there's no compelling reason, I'll commit my modifications to svn.

--William