[Wannier] Reciprocal vectors in wannier90 vs Quantum espresso

[Youssef Aharbil]

Dear Giovanni,

I got it, Thank you for the clarification and have a nice week-end.

Youssef Aharbil,
Laboratory of Physics and Chemistry of Materials
Faculty of sciences Ben msik, Casablanca
Morocco



2016-12-03 22:26 GMT+00:00 Giovanni Cantele <
giovanni.cantele at fisica.unina.it>:

> they are the same but printed in different units, Wannier90 in Ang^-1, QE
> in 2*pi/a units.
>
> If you multiply the QE reciprocal vectors by 2*pi/a = 2*pi/alat = 2 * pi /
> (10.577485*0.529177) Ang^-1 = 1.1225262 Ang^-1 you exactly get the
> Wannier90 ones.
>
> Giovanni
>
>
> On 3 Dec 2016, at 21:54, Youssef Aharbil <aharbil at gmail.com> wrote:
>
> Dear All,
>
> I have noticed that the reciprocal vectors computed via wannnier90 and
> quantum espresso (QE) are different***, which means that the Kpath and
> segment length across the BZ aren't the some for both code though handling
> the same crystal structure.
>
>
>
> In order to investigate this issue, I have dug inside the source code of
> wannier90 and QE and compared the formula used in each code and finally
> realized the root cause, In fact QE divide the reciprocal vectors by an
> additional term, the real space vector denominator (den variable in
> recips.f90), which isn't the case for wannier90 (utility.F90).
>
> So, I am really confused, I can manually fix this, but I wanted to share
> with you.
> Any suggestions or clues are most welcome.
>
>
> ***
> Wannier90 header:
>
>                                     ------
>                                     SYSTEM
>                                     ------
>
>                               Lattice Vectors (Ang)
>                     a_1     2.784694  -1.607742   4.581610
>                     a_2     0.000000   3.215484   4.581610
>                     a_3    -2.784694  -1.607742   4.581610
>
>                    Unit Cell Volume:     123.07314  (Ang^3)
>
>                         Reciprocal-Space Vectors (Ang^-1)
>                     b_1     1.128164  -0.651347   0.457131
>                     b_2     0.000000   1.302693   0.457131
>                     b_3    -1.128164  -0.651347   0.457131
>
>
> QE Header:
>
>      celldm(1)=  10.577485  celldm(2)=   0.000000  celldm(3)=   0.000000
>      celldm(4)=   0.504986  celldm(5)=   0.000000  celldm(6)=   0.000000
>
>      crystal axes: (cart. coord. in units of alat)
>                a(1) = (   0.497501  -0.287232   0.818530 )
>                a(2) = (   0.000000   0.574464   0.818530 )
>                a(3) = (  -0.497501  -0.287232   0.818530 )
>
>      reciprocal axes: (cart. coord. in units 2 pi/alat)
>                b(1) = (  1.005024 -0.580251  0.407234 )
>                b(2) = (  0.000000  1.160501  0.407234 )
>                b(3) = ( -1.005024 -0.580251  0.407234 )
>
>
> Youssef Aharbil,
> Laboratory of Physics and Chemistry of Materials
> Faculty of sciences Ben msik, Casablanca
> Morocco
>
>
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>
>
>


-- 
والله ولي التوفيق
يوسف أحربيل
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