[QE-users] Soft Hydrogen Pseudopotentials

[Giuseppe Mattioli]

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>