[Pw_forum] ecutvcut in Hybrid functionals

[Layla Martin-Samos]

Dear Amin, ecutvcut is ignored is exxdiv_treatment is different from
vcut_ws. Which is the case by default. We leave this variable there only
because you could have chosen to set exxdiv_treatment="ecut_ws", and in
this case (and ONLY in this case) you need a reasonable value for ecutvcut.

cheers

Layla

2012/11/23 Amin Torabi <mtorabi at uwo.ca>

> Dear Layla
>
> You said that "ecutvcut is a parameter which is not strictly bonded to
> hybrid functional parameters, but to strongly anisotropic supercells"
> So, why do we have ecutvcut=0.7 in the PBE0 example for bulk Si?
>
>
>
>
> On Fri, Nov 23, 2012 at 2:31 AM, Layla Martin-Samos <
> lmartinsamos at gmail.com> wrote:
>
>> Dear Leonardo and Jianpeng, the "issue" is that HSE contain only the
>> shortrange part of coulomb potential for the fock term (thas why HSE
>> contain an exponential with a screening lenght). Ecutvcut, spehrical cutoff
>> and all similar tricks APPLY ONLY for the "REAL" Coulomb potential, the
>> FULL Coulomb potential. So, one has to be very careful when dealing with
>> hybrids that do not contain the full coulomb potential.
>>
>
>
>
> --
> ***************************************
> Amin Torabi
> Ph.D. Student
> Chemistry Dept.
> Western University
> London, On Canada, N6A 5B7
> Phone: 519-661-2111 Ext: 87871
> ****************************************
>
>
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