[Wannier] (no subject)

Aron Szabo szaboa at iis.ee.ethz.ch
Thu Mar 26 14:54:28 CET 2015

Dear Khalid,

the initial projections can affect whether the wannierization process 
finds the global minimum or just a local one. So you will most likely 
get more compact functions if you use good projections than if you use 
random projections. But you can give it a try, and check what is the 
spread of the resulting Wannier functions. They should be around just a 
few Angstroms (2-3 in my experience for semiconductors, but can be more 
depending on the system). Also, the Hamiltonian should be real when you 
are at the global minimum (use hr_plot = T to check it).

If you don't know anything about the character of the electronic states 
in your system, then you should first project the Bloch functions onto 
atomic orbitals centered on the ions, and check which orbitals on which 
ions dominate in those bands that you want to reproduce with Wannier 
functions. In VASP you need to set the LORBIT = 10 tag to generate these 
orbital projections. It can give you an idea about which orbitals and 
how many of them you need.

Aron Szabo

On 03/26/2015 02:29 PM, Khalid Ibne Masood Khalid wrote:
> Dear Researchers,
> I am new to wannier90, and I apologize my physics is not good enough. 
> I have two questions:
> 1) When writing wannier input file (.win file) I have found the 
> projection block most painful. I am not sure where and which orbitals 
> to choose. (how many s and p should be taken?) Does this initial 
> approximated projection affect the final transport result? If I take 
> random projections, will that be okay in transport problems ?
> 2) I want to consider the effect of electrical field in transport 
> properties, for this I can take electric field in my DFT calculations, 
> but I was wondering whether I take the gamma only option with electric 
> field in my DFT calculation, will it be allowed in wannierisation ?
> Thank you.
> _______________________________________________
> Wannier mailing list
> Wannier at quantum-espresso.org
> http://mailman.qe-forge.org/cgi-bin/mailman/listinfo/wannier

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