[Wannier] Issue with convergence

[Li, Junwen]

Dear Carlo,

In a perovskite material the valence bands near the Fermi level are mainly derived from the s orbital of Pb and the p orbital of Br. There are also some contributions from the p orbital of Pb and the s orbital of Br. So s and p orbitals for both Pb and Br should be included in the calculations for the perovskite materials.

Junwen Li
Postdoctoral Research Associate
Energy Research Group
National Institute of Standards and Technology
Gaithersburg, MD  20899 USA

-----Original Message-----
From: Wannier [mailto:wannier-bounces at quantum-espresso.org] On Behalf Of Carlo Motta
Sent: Tuesday, October 06, 2015 5:49 AM
To: wannier at quantum-espresso.org
Subject: [Wannier] Issue with convergence

Dear Wannier90 users,

I write to ask for some help.
I am trying to wannierize the valence band of a perovskite material, I tried with many initial centers but it seems that I am not able to converge the calculation.
I reach a value of Delta~1E-14 but then it increases and does not converge. I think that in order to have a good result I should reach something on the order of E-20.

However, even if I stop the calculation once the E-14 Delta has been reached (by tuning num_iter), the XSF file contains all NaN, which is worrying me.

Could anyone give me a hint?

Thank you in advance,


--
              
Carlo Motta

PostDoc Researcher
School of Physics and CRANN,         
Trinity College Dublin,                         
Dublin 2, IRELAND
http://sites.google.com/site/carlomottaphd