[QE-users] Generating fractional charged hydrogen PPs

[Felix Mayr]

So, just as when this question was asked in February, things came up 
this time and so this reply (and the thanks to all of you!) is a little 
bit overdue.

> https://www.mail-archive.com/users@lists.quantum-espresso.org/msg35407.html

If I interpret this thread correctly this is just something which either 
works or doesn't. Specifically this works well for me (and others 
https://www.mail-archive.com/users@lists.quantum-espresso.org/msg34321.html), 
so I guess I'm fine (reducing the number of layers I need for a 
GaN-oxide-slab to have a reasonable electronic structure, which 
reproduces published results). Interesting note on the forces though 
(which I don't care for, since I keep the lower layers fixed).

> Another approach is to calculate a dipole correction and apply a potential to your slab.
> You’re mileage may vary. You can read (and test) more here:https://christoph-wolf.at/2018/05/02/dipole-correction-in-quantum-espresso/ 
(Courtesy C. Wolf).

Up to now I thought this were 2 distinct problems. With the fractional 
"PPs" I get the things right "qualitatively" (right amount of e, no 
unsaturated bonds), the dipole corrects the energy-levels 
"quantitatively" (and allows alignment to the vacuum).

> After generating pseudopotentials in the same way Paolo suggested I moved
> on and tried the same procedure with the PSlibrary ld1.x input files for
> hydrogen. I just simply replaced zed, config, zval and ocs (in the
> PseudoPotentialGenerationCard (see also the ld1.x input description)) to
> these fractional charges I was interested in.

Well, I tried that too but apparently I should have gone a step back and 
tried with NC first (though for "setup-consistency"-reasons this isn't 
much better). If I find time, I'll check this again and will share any 
news here, thanks a lot for the sample!

Best Regards

-- 
Felix Mayr, B.Sc.
research assistant

Technical University of Munich
Department of Electrical and Computer Engineering
Simulation of Nanosystems for Energy Conversion

Arcisstraße 21
80333 Munich, Germany

email: felix.mayr at tum.de
phone: +49-89-289-26933