[Wannier] Constrain to the minimization

[Mostofi, Arash]

Hi,
The maximal localization criterion does result in mixing the occupied pi and sigma manifolds - there is a discussion in Sec III.A of Rev Mod Phys 84, 1419 (2012). You can usually achieve separation at the expense of also including the unoccupied pi* manifold to give you an atom-centred and partly-occupied pz orbital on each C and a bond-centred sigma orbital on each C-H and C-C bond.
Best wishes,
Arash

—
Dr Arash Mostofi — www.mostofigroup.org<http://www.mostofigroup.org>
Imperial College London
Director, Thomas Young Centre @Imperial
Assistant Director, CDT in Theory & Simulation of Materials
Warden, Wilkinson & Weeks Hall




On 24 Nov 2014, at 21:44, xiaochuan Ge <ustc.scgyer at gmail.com<mailto:ustc.scgyer at gmail.com>> wrote:

Dear all,

For example I have a conjugated carbon chain ( CH2-(CH)n-CH2) which I expect to show two types of wannier functions: Sigma-like orbitals sitting on carbon-hydrogen and carbon-carbon bonds, and Pi-like orbitals that sits on two carbons. However, it occurs that wannier90 always mixes the Pi-like orbital with one of the sigma-like orbitals in order lower the localization. I understand this may produce more localized orbitals, but the shape of them have less chemical meaning.

What I would like to do is to separate the occupied KS orbitals into two manifolds: pi-like orbitals ( they look like the linear combination of Carbon-pz orbital), and the rest. Then when we I rotate the KS orbitals in order to produce Wannier functions I do not mix the orbitals between these two manifolds.

I hope I have explained the question clear enough. Has this kind of thing or similar already been considered in wannier90? Would anyone suggest me how to achieve this? Thank you very much.

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Dr. Xiaochuan Ge (Giovanni)
Center for Functional Nanomaterials
Brookhaven national laboratory
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