[Pw_forum] k point grid hybrid functionals

["Valentina Dellacà C.R.F. S.C.p.A."]

Dear Lorenzo,
thank you very much. Your answer is very helpful.
If someone has a paper to suggest me...thanks.
Regards,
Valentina



Il 04/15/2013 03:19 PM, Lorenzo Paulatto ha scritto:
> On 04/15/2013 02:33 PM, "Valentina Dellacà C.R.F. S.C.p.A." wrote:
>> Dear Lorenzo,
>> thanks for your answer. I still have some doubts; when you say that
>> 'In the limit where the {q} grid contains only the Gamma point, than
>>      each k-point exchanges only with itself (not with Gamma!).'
>> it means that the q+k grid will end up to be the k grid. But then,
>
> No, it does not. In fact there is not a single {k+q} grid, there is 
> one for each k point. In the first case each of these grids contain a 
> single point: k itself. In the second case, each of this grids contain 
> all the k points, but in a different order and eventually translated 
> by a G vector.
>
> The second condition I stated before guarantees that k+q = Sk'+G, for 
> every k and q, where k' is a point in the {k} grid, S a symmetry 
> operation and G a vector of the reciprocal lattice. If you ignore 
> symmetry, you can restate the condition as, it must be possible to 
> express any q as q= k-k'+G, same definitions as before.
>
> This allows to store all the {k+q} grids very efficiently, but you 
> should still think of them as many different grids.
>> As you see, I am a beginner and a bit confused about this topic, do 
>> you have any paper to recommend me?
>>
> I do not have any paper where this is mechanism is explained in 
> detail... maybe someone else who's reading this thread can recommend 
> some reading?
>
> bests
> -- 
> Dr. Lorenzo Paulatto
> IdR @ IMPMC -- CNRS&  Université Paris 6
> phone: +33 (0)1 44275 084 / skype: paulatz
> www:http://www-int.impmc.upmc.fr/~paulatto/
> mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05


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