[Pw_forum] Warnings

[Subhradip Ghosh]

Hi,

I am trying to test the convergence of Gamma and X phonons for a simple
metal in fcc structure.

I got the convergence of Gamma phonons using a high plane-wave cut off (60
Ryd), a dense k-space mesh(22x22x22) using M-P smearing and without any
offset in the k-mesh. Using the conjigate-greadient diagonalization for
the scf part I always got warnings '1 eigenvector did not converge' at the
last iteration. Therefore, I used Davidson diagonalization which took care
of the warning.

When I try to test the convergence of X phonons, I used the same set of
parameters for the nscf calculation. Using the Davidson diagonalization
for the nscf part I get hundreds of warning '1 eigenvector did not
converge'. I then used Conjugate-gradient diagonalization for the nscf
part to see if it takes care of the problem. To my astonishment, the
warning is still there, albeit less in number. To my understanding, under
such circumstances, one should not trust the X phonon results.

Can somebody suggest a way out?

Regards,

Subhradip


-- 
************************************************************************
			Dr. Subhradip Ghosh
			Assistant Professor
			Department of Physics
		Indian Institute of Technology, Guwahati
			North Guwahati, Assam-781039
				India
			E-mail: subhra at iitg.ernet.in
			Phone: +91 361 2582717(O)
                               +91 361 2584717(R)
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