[Wannier] charge of wannier function
Hu Shuanglin
hushuanglin at gmail.com
Fri Jun 29 12:19:37 CEST 2012
Dear all,
I am new to wannier90, and try to use wannier90 and vasp together.
I thought since wannier function is the unitary transfromation of
Bloch functions,
1, each wannier centers here should correspond to one charge center,
and each could
be occupied by 2 electrons (without spin-polarization).
2, from the occupied wannier functions, I can do summation to get the
overall charge
density that equal to vasp CHGCAR data.
Is this understanding correct?
Then in order to test this, I added some lines like following in the
plot.F90 file:
wann_rho(nxx,nyy,nzz,loop_w)=
wann_func(nxx,nyy,nzz,loop_w)*conjg(wann_func(nxx,nyy,nzz,loop_w)
wann_chg(nxx,nyy,nzz)= wann_chg(nxx,nyy,nzz)+wann_rho(nxx,nyy,nzz,loop_w)
sum_rho(loop_w)=sum_rho(loop_w)+wann_rho(nxx,nyy,nzz,loop_w)
After the summation, the "electron number of each wannier function" is
printed out
sum_rho(loop_w)=sum_rho(loop_w)/(ngs*ngx*ngs*ngy*ngs*ngz)
I am studying a insulator LiOH, in which there are 16 valence
electrons in one unit cell,
and vasp gave a default num_wann=8 in the .win file. The loop_w is
looped over all the 8
occupied band in this model, and only Gamma point is used in k-space.
However, I get a number lower than 1 for one wannier band, and they do
not equal to each
other between wannier bands.
Wannier Function Num: 1 Number of Charge = 0.843700E+00
Wannier Function Num: 2 Number of Charge = 0.843700E+00
Wannier Function Num: 3 Number of Charge = 0.833333E+00
Wannier Function Num: 4 Number of Charge = 0.832989E+00
Wannier Function Num: 5 Number of Charge = 0.832841E+00
Wannier Function Num: 6 Number of Charge = 0.810597E+00
Wannier Function Num: 7 Number of Charge = 0.833188E+00
Wannier Function Num: 8 Number of Charge = 0.810594E+00
In this case, the total number of electrons will certainly not to be 8*2=16.
Is there anything wring in my understanding or inplementation? Any
comments could be helpful.
Thank you!
Best Regards,
Shuanglin Hu
--
Department of Chemistry - the Angstrom Lab
Uppsala University
Box 538, SE 751-21
Uppsala, Sweden
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