[QE-users] Soft Hydrogen Pseudopotentials

[Matthieu Fortin-Deschênes]

Thanks Giuseppe,

I actually want to passivate the bottom of Si and Ge surfaces, as well  
as one edge of a 2D nanoribbon (antimonene).
I believe fractional charge H atoms would not be useful for these  
kinds of materials. Right?

I was not aware of this strong dopant effect, but I'd be interested in  
reading more about it if you have any reference to suggest.

Thank you,

Matthieu

Giuseppe Mattioli <giuseppe.mattioli at ism.cnr.it> a écrit :

> Dear Matthieu
> I don't know which surface you want to passivate, but remember that  
> H can also have a strong dopant effect on surfaces (e.g., a large  
> upward shift of both band edges, which has been measured on  
> C-diamond). Therefore, I used to passivate the unreconstructed end  
> of III-V slabs with *pseudo* H atoms, having fractional charge which  
> simulate a bulk environment surrounding the bottom layer of the  
> slab. They used to be in the online library but they are not anymore  
> (maybe for good reasons which I don't know). If you want to try I  
> can send you the UPF files. They are NC VBC pseudopotentials which  
> should not require more than ecutwfc=40: after all you are not  
> interested in structural rearrangement but you only need electronic  
> passivation of surface states.
> HTH
> Giuseppe
>
> Quoting Matthieu Fortin-Deschênes <matthieu.fortin-deschenes at polymtl.ca>:
>
>> Hi all,
>>
>> I want to use hydrogen to passivate the bottom surface of a surface  
>> slab. However, I notice that H PPs usually require a high ecutwfc,  
>> which restricts the size of the system I can consider.
>>
>> Are there any PPs with lower required ecutwfc available for that purpose?
>> And would this negatively effect the accuracy of the calculations  
>> on the other side of the surface slab?
>>
>> Thank you,
>>
>> Matthieu Fortin-Deschênes
>> Polytechnique Montréal
>>
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>
>
> GIUSEPPE MATTIOLI
> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
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