[Wannier] 回复: Query about wannier90 calculations on disordered supercell

[Stepan Tsirkin]

Hi Mouyang,


Tecnically it is ok to wannierise from a 1x1x1 when the unit cell is 
big. For example, in fig 5a of this paper 
https://iopscience.iop.org/article/10.1088/1361-648X/ab51ff/meta#cmab51fff05 
an example is shown of a 12-atom carbon chain that was wannierised from 
Gamma-point only and the dispersion is restored with the MDRS method. 
So, technicall Boltzwann can do the calculation even if the 
wannierisation started from Gamma-point only. It will correctly 
interpolate the bands to any grid of k-points and take the derivatives.


But if it makes sense physically - is another question. The 
semiclassical equations of motion (underlying the Boltzwann) are defined 
for  crystals. I guess the condition is that mean-free-path is much 
larger then the size of the unit cell.


May be you can use the Wannier model to study quantum transport (See 
chapter 7 of the user guide 
https://raw.githubusercontent.com/wannier-developers/wannier90/v3.1.0/doc/compiled_docs/user_guide.pdf) 
but I am not an expert in that.


Best,

Stepan.



On 31.10.23 02:02, Mouyang Cheng wrote:
> Dear Stepan,
>
> Thanks for the reply, and sorry for my late response. Yes, I did try 
> to make the k-mesh 1*1*1 and perform the wannierlization at this 
> accuracy. I think my question is whether this approach gives a 
> reasonable tight-binding model at the DFT-level? Because I feel 
> strange for wannier90 only fitting one k-point for each energy level 
> to get so many localized wavefunctions.
>
> Another problem is that at first I tried to perform further transport 
> simulation in Boltzwann, but Boltzwann calculation requires 
> information on multiple k-points to do derivatives, (i.e. it needs a 
> whole band). So I guess the alternative is to wannierlize first, then 
> carry out tight-binding simulation on transport by other means?
>
> Really appreciate your advice and help!
>
> Best regards,
> Mouyang
> ------------------------------------------------------------------------
> *发件人:* Stepan Tsirkin <stepan.tsirkin at ehu.eus>
> *发送时间:* 2023年10月27日 20:42
> *收件人:* Mouyang Cheng <vipandyc at mit.edu>; 
> wannier at lists.quantum-espresso.org <wannier at lists.quantum-espresso.org>
> *主题:* Re: [Wannier] Query about wannier90 calculations on disordered 
> supercell
>
> Dear Mouyang,
>
>
> As I understand, there is no fundamental obstruction to make the 
> k-mesh 1x1x1, So you will have a Gamma-only sampling. Although I do 
> not have experience in that. Did you try that, and did you come across 
> some difficulties?
>
>
> Best Regards,
>
> Stepan
>
>
>
> On 26.10.23 05:15, Mouyang Cheng wrote:
>> Dear Wannier90 developers,
>>
>> This is Mouyang Cheng, a student at MIT. I'm interested in generating 
>> wannier orbitals for disordered systems, e.g. amorphous 2D graphene 
>> sheet (large disorder). I've read several articles successfully 
>> coping with applying generalized Wannier orbitals on disordered 
>> systems like:
>> Maximally-localized Wannier functions for disordered systems: 
>> Application to amorphous silicon - ScienceDirect 
>> <https://www.sciencedirect.com/science/article/abs/pii/S0038109898001756>;
>>
>> However as to my understanding in the user manual of Wannier90, we 
>> need to specify the Kmesh and number of bands to do wannier fit. But 
>> for a large supercell (~200 atoms) it is only practical for DFT to 
>> deal with only one Gamma point for BZ, and there is no concept of 
>> band in non-crystals.
>>
>> *So my question is: can Wannier90 deal with such an amorphous 
>> supercell and get a tight-binding Hamiltonian? *If not, could you 
>> give any suggestions on any other code or convenient methods; If yes, 
>> how does it work?
>>
>> Thank you so much for taking your time reading this email and I would 
>> greatly appreciate any help or clarification.
>>
>> Best regards,
>> Mouyang Cheng
>>
>> NSE, Massachusetts Institute of Technology
>> <https://www.sciencedirect.com/science/article/abs/pii/S0038109898001756>
>> 	
>> Maximally-localized Wannier functions for disordered systems: 
>> Application to amorphous silicon 
>> <https://www.sciencedirect.com/science/article/abs/pii/S0038109898001756>
>> We use the maximally-localized Wannier function method to study 
>> bonding properties in amorphous silicon. This study represents, to 
>> our knowledge, the …
>> www.sciencedirect.com <http://www.sciencedirect.com>
>>
>>
>>
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