[QE-users] Current use of hybrid xc-functionals (PBE0/HSE)

Giuseppe Mattioli giuseppe.mattioli at ism.cnr.it
Wed Aug 15 19:29:29 CEST 2018


Dear Chris
EXX functionals currently work very well in QE. Recent versions  
implement the automatically compressed exchange algorithm as a default  
solver for exx which speeds up the job. Please play also around with  
two very useful keys such as ecutfock (cutoff for Fock density,  
ecutfock=ecutwfc is very fast, ecutfock=2*ecutwfc is very accurate)  
and adaptive_thresh (sorry if it is misspelled, I’m quoting by  
hearth), which lowers the wfc threshold of inner scf cycles far from  
convergence. However, this nice report holds in my (quite large)  
experience only if you use norm conserving pseudopotentials: the  
calculation is more stable and also faster (density cutoff is quite a  
bottleneck). ONCV PPs may be a nice starting point, but you must stick  
to PBE. An implementation of native EXX PPs would be a very good  
improvement. AFAIK, there is an experimental implementation in the  
generation of PBE0 PPs in OPIUM, but I have never tested it.
HTH
Giuseppe


chris sewell <chrisj_sewell at hotmail.com> ha scritto:

> I’m well versed in the theory of PBE0 and HSE06 (having used them in  
> the CRYSTAL code), but to implement in QE (and plane-wave codes in  
> general) is there any additional considerations?
>
> As far as I understand, there is currently no pseudopotentials  
> specifically available for HSE/PBE0?
>
> Can I then simply use my setup for PBE+PAW, with for example this  
> pseudopotential; Fe.pbe-spn-kjpaw_psl.0.2.1.UPF, and add the option:  
> input_dft='HSE' (and optionally set the alpha and screening  
> parameters)?
>
> I hope this is not a repeat of a previous question, but the only  
> information I could find was in a 2010 post;  
> http://lists.quantum-espresso.org/pipermail/users/2010-May/016986.html
>
> Kind Regards,
> Chris


GIUSEPPE MATTIOLI
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
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E-mail: <giuseppe.mattioli at ism.cnr.it>



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