[Wannier] How to build tight binding (TB) dispersion relations from seedname_hr.dat file of Wannier-90 output

[Soumyadeep]

Dear Kenan,

     Thanks for the information regarding Hamiltonian, I will check and 
write you back. What is the minimum amount of spread for well converged 
wannierization? How to choose proper kmesh for wannierization, for SCF 
calculation I use convergence test over large number of k-sets?

thanks you very much and best regards
Soumyadeep

On 08-03-2019 17:19, Kenan Song wrote:
> Dear Soumadeep,
> 
> I think that the n and m value indicate the Hamiltonian matrix element
> position and R vector (R1, R2 and R3) indicates the phase factor in
> the tight binding model. For example, 1 2 1 2 3 1.5 0.0, following the
> sequence of R1 R2 R3 n m H_real H_imag, indicates that H23 element is
> 1.5 * EXP(-i * (1 * a1 + 2 * a2 + 1 * a3) * (kx + ky + kz)). a1 ~ a3
> are the lattice vectors in real space and kx ~ kz are the coordinates
> of k point along three axes in reciprocal space.
> 
> Regarding the imaginary part of the matrix element, it is supposed to
> be zero or a very small value. If it is not, I think that the k point
> mesh is too loose or the wannierization is not well done. This is my
> own understanding and I hope that it could help you.
> 
> Kind regards,
> 
> Kenan Song
> 
> On Fri, Mar 8, 2019 at 2:35 PM Soumyadeep <soumyadeep at rrcat.gov.in>
> wrote:
> 
>> Dear W90 experts,
>> 
>> I am a new user of wannier-90 code, apologize for the nature of
>> this
>> question that having much previous discussion. My aim is to build TB
>> 
>> dispersion relations as mention in the following paper's appendix
>> section (pg.9),
>> 
>> https://journals.aps.org/prb/abstract/10.1103/PhysRevB.96.094521
>> 
>> Up to my  knowledge it can be build using parameters of
>> seedname_hr.dat file. But this file contains num_wanXnum_wan matrix
>> elements for each lattice vectors. Once I fixed my nearest
>> neighbours
>> how to construct such dispersion relations?
>> 
>> Structure of this file is,
>> R1    R2    R3    n    m   H_real    H_imag
>> 
>> Is H_imag must be zero in practical cases? If yes how to make
>> them
>> zero?
>> 
>> thanks in advance and regards
>> Soumyadeep
>> 
>> -------------------------------------------------------------------
>> Soumyadeep Ghosh,
>> Senior Research Fellow,
>> Indus Synchrotrons Utilization Division,
>> Raja Ramanna Centre for Advanced Technology, Indore, India-452013
>> Mob: (+91)9424664553
>> User Lab: 0731244-2580
>> Email: soumyadeepghosh35 at gmail.com, soumyadeep at rrcat.gov.in
>> -------------------------------------------------------------------
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> 
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