[QE-users] Soft Hydrogen Pseudopotentials

[Matthieu Fortin-Deschênes]

Thanks for the info. I'll take a look at those papers.

Matthieu

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

>> I believe fractional charge H atoms would not be useful for these  
>> kinds of materials. Right?
>
> I suppose you are right. I can only suggest you to double check the  
> results and to carefully compare with experimental results obtained  
> on real systems. I cited C-diamond, which is "akin" to Si and Ge,  
> because surface hydrogenation induce a large upward shift of both  
> valence and conduction bands, measured by ARPES and compared with  
> DFT calculations here: Phys. Rev. B 94, 045307 (2016)
>
> Surface or interstitial H is a well known dopant in semiconductors.  
> Among tons of papers (I'm ashamed to cite mine :-)) I can suggest  
> the classical Van de Walle Nature paper on universal alignment of H  
> (Nature 423, 626, 2003)
>
> HTH
> Giuseppe
>
> Quoting Matthieu Fortin-Deschênes <matthieu.fortin-deschenes at polymtl.ca>:
>
>> 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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>>> E-mail: <giuseppe.mattioli at ism.cnr.it>
>>>
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>>
>>
>>
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>
>
> GIUSEPPE MATTIOLI
> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
> Via Salaria Km 29,300 - C.P. 10
> I-00015 - Monterotondo Scalo (RM)
> Mob (*preferred*) +39 373 7305625
> Tel + 39 06 90672342 - Fax +39 06 90672316
> E-mail: <giuseppe.mattioli at ism.cnr.it>
>
> _______________________________________________
> users mailing list
> users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users