[Wannier] Atomic centres translations and lack of WFs localization

[Krzysztof Kosmider]

Dear all,

I calculate with VASP a nanotube (along z axis) made of 64 atoms
and then calculate 242 WFs by Bloch states projection over atomic
orbitals (p and d)  with radially oriented z-axis (x-azis along a nanotube).
(I did before successfully monolayer wannierization)

If I switch-on guiding centres (guiding_centres=.true.) and avoid
minimization procedure (num_iter=0), I obtain a basis of WFs with
a spread not greater than 2.0 A^2.
However, without guiding centres (guiding_centres=.false.) all
atomic centres are translated significantly (so that a sum of centres lies
on the  x=0.0 y=0.0 axis) and, most importantly, some of the WFs loose
localization (spread about 100 A^2). The same happens when I keep
guiding centres but allow minimization (even for num_iter=1).

With such a not maximally localized basis I obtain meaningful information
about electronics of  the system. I wonder, however, what is a reason of
those translations and why this causes a lack of WF's localization?
How to perform total spread minimization in my case?

Thank you in advance,
Krzysztof Ko?mider

INL - International Iberian Nanotechnology Laboratory
Av. Mestre Jos? Veiga s/n
4715-330 Braga
Portugal

email: kkusiu at gmail.com


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