It is my pleasure to write to you.
I am a postgraduate student in Tsinghua university.
I am calculating phonon dispersion with quantum espresso.
And I am using materialscloud to creat K ponits on line.
I would like to ask some questions about units of q points in matdyn.in.freq
files.
For example , H point for MgB2 , is (0.3333 0.3333 0.5) with scaled units
created on materialscloud or using Materials Studio.
My question is whether H (0.3333 0.3333 0.5) be used directly in matdyn.in
files to calculate phonon dispersion.
In the matdyn.in files , Kpoint's unit is "2pi/alat" ,so it's wrong to use H
(0.3333 0.3333 0.5) directly?
So I convert H (0.3333 0.3333 0.5) to （0.333333 0.57735 0.437548）with
2pi/alat units , and here is my ways,I don't konw whether it's right ？ Or how
to convert it ?
First , scf.out contains information about "reciprocal axes: (cart. coord. in
units 2 pi/alat)", it's
b(1) = ( 1.000000 0.577350 -0.000000 )
b(2) = ( 0.000000 1.154701 0.000000 )
b(3) = ( 0.000000 -0.000000 0.875096 )
Then , H point with scaled units is ( 0.3333 0.3333 0.5 ) ,
equals to 0.3333*b(1）+0.3333*b(2)+0.5*b(3) with unit 2pi/alat，
because in scf.out files :
b(1)= 1*2pi/alat(1)+0.577350*2pi/alat(2)+0*2pi/alat(3),
b(2)= 0*2pi/alat(1)+1.154701*2pi/alat(2)+0*2pi/alat(3),
b(3)= 0*2pi/alat(1)+0*2pi/alat(2)+0.875096*2pi/alat(3),
Finally, H points convert to （0.333333 0.57735 0.437548）with unit
2pi/alat,
which equals to row vector H multify matrix B=[ b(1) ; b(2) ; b(3) ]
= H*B=（0.333333 0.57735 0.437548）with 2pi/alat units.
Is this the right method to convert high symmetry q points ?
Or how to convert the q points with scaled units to those with 2pi/alat?_______________________________________________
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