Re: [Wien] Wannier

2024-02-15 Thread Mikhail Nestoklon via Wien

Dear Lukasz,
Wannier basis is pretty similar to TB basis, but they are not fully equivalent. 
In Wannier basis Hamiltonian contributions from quite distant neighbors are 
important, they are not automatically localized on atoms, have proper symmetry, 
etc.
I recommend to check the following papers where proper TB is constructed from 
the Wannier functions:
https://doi.org/10.1103/PhysRevB.92.085301
https://doi.org/10.1103/PhysRevMaterials.2.103805
https://doi.org/10.1103/PhysRevB.99.125117
 
Sincerely yours,
Mikhail
 
 
 
 
 
  
>Четверг, 15 февраля 2024, 1:41 +01:00 от pluto via Wien 
>:
> 
>Dear All,
>
>I am interested to project WIEN2k band structure onto atomic orbitals,
>but getting complex amplitudes. For example, for graphene Dirac band
>(formed primarily by C 2pz) I would get two k-dependent complex numbers
>A_C2pz(k) and B_C2pz(k), where A and B are the two inequivalent sites,
>and these coefficients for other orbitals (near the Dirac points) would
>be nearly zero. Of course, for graphene I can write a TB model and get
>these numbers, but already for WSe2 monolayer TB model has several bands
>(TB models for WSe2 are published but implementing would be
>time-consuming), and for a generic material there is often no simple TB
>model.
>
>Some time ago I looked at the WIEN2k wave functions, but because of the
>way LAPW works, it is not a trivial task to project these onto atomic
>orbitals. This is due to the radial wave functions, each one receiving
>its own coefficient.
>
>I was wondering if I can somehow get such projection automatically using
>Wien2Wannier, and later with some Wannier program. I thought it is good
>to ask before I invest any time into this.
>
>And I would need it with spin, because I am interested with systems
>where SOC plays a role.
>
>The reason I ask:
>Simple model of photoemission can be made by assuming coherent addition
>of atomic-like photoionization, with additional k-dependent initial band
>amplitudes/phases. One can assume that radial integrals in photoemission
>matrix elements don't have special structure and maybe just take atomic
>cross sections of Yeh-Lindau. But one still needs these complex
>coefficients to allow for interference of the emission from different
>sites within the unit cell. I think for a relatively simple material
>such as WSe2 monolayer, the qualitative result of this might be
>reasonable. I am not aiming at anything quantitative since we have
>one-step-model codes for quantitative.
>
>Any suggestion on how to do this projection (even approximately) within
>the realm of WIEN2k would be welcome.
>
>Best,
>Lukasz
>
>
>PD Dr. Lukasz Plucinski
>Group Leader, FZJ PGI-6
>Phone:  +49 2461 61 6684
>https://electronic-structure.fz-juelich.de/
>
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Re: [Wien] BoltzTrap-electronic thermal conductivity

2024-02-15 Thread Gavin Abo
Your understanding is correct.  The BoltzTraP code solves an 
approximation of the electronic Boltzmann transport equation that 
outputs electronic thermal conductivity per relaxation time (ke/τ).


On the other hand, the phonon Boltzmann transport equation for example 
has to be solved to get the lattice thermal conductivity (kl). almaBTE 
is a code for VASP [1] and phono3py is a code for Quantum Espresso (QE) 
[2]. Unfortunately, I have yet to find one that supports WIEN2k.


If you're referring to the unsupported user contributed 
add_boltz2_to_w2web that hasn't been maintained to work with the latest 
bug fixed [3] WIEN2k version, then that add_boltz2_to_w2web package did 
output an incorrect ZT value assuming kl =0 in its calculation.


For example, the LaFe3CoSb12 experimental zT value at 300 K is 0.14 in 
Table I of the paper titled "Seebeck Coefficient and the Thermoelectric 
Figure of Merit in Semiconductors and Conducting Polymers" by B. F. 
Howell et al at [4].


If kl is ignored, ZT is computed as 0.54 which is far from the 
experimental value of 0.14.


ZT ≈ σS^2T/ke = {6.3860e+04 1/(ohm*m)}*{1.0090e-04 V/K}^2*{300 K}/{0.36 
W/(K*m)} = 0.54


On the other hand, when kl is included, the computed value of 0.12 is 
close to the experimental value of 0.14.


ZT ≈ σS^2T/(ke + kl) = {6.3860e+04 1/(ohm*m)}*{1.0090e-04 V/K}^2*{300 
K}/{0.36 W/(K*m) + 1.26 W/(K*m) } = 0.12


[1] https://almabte.bitbucket.io/
[2] https://phonopy.github.io/phono3py/
[3] http://www.wien2k.at/reg_user/updates/
[4] Accession Number ADA327846 at: https://ntrl.ntis.gov/NTRL/

Kind Regards,

Gavin
WIEN2k user

On 2/15/2024 2:14 AM, Bara abujafar via Wien wrote:
I would like to inquire about the BoltzTraP code implemented in the 
WIEN2k package. I am uncertain whether it neglects lattice thermal 
conductivity, as there are conflicting claims suggesting that 
BoltzTrap may only focus on electronic thermal conductivity. Your 
feedback on this matter would be greatly appreciated.

With best regards
Mohammed Abu-Jafar___
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[Wien] BoltzTrap-electronic thermal conductivity

2024-02-15 Thread Bara abujafar via Wien
I would like to inquire about the BoltzTraP code implementedin the WIEN2k 
package. I am uncertain whether it neglects lattice thermalconductivity, as 
there are conflicting claims suggesting that BoltzTrap mayonly focus on 
electronic thermal conductivity. Your feedback on this matterwould be greatly 
appreciated. With best regardsMohammed Abu-Jafar
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