Dear all;
And I am trying to reproduce the results for NbLi(SLN) of this paper:
PHYSICAL REVIEW MATERIALS 1, 054406 (2017)
Although I could calculate the band structure of the plain lithium niobate, I
have some difficulties in my Hubbard calculations and I really appreciate it if
you could please guide me through that.
Nb sits in Li site with +5 charge, but since Li already has +1, I defined
the total charge of the unit cell as +4. I am also setting the occupations of
the substitutional Nb manually, so that I have 4 spin ups and zero spin downs.
(I have attached my input file)
Below, is a section of my output. Although the occupations are set to the
manual ones, after a scf iteration, it changes to incorrect and partial
occupations! Also, the number of orbitals treated with Hubbard term is printed
as 3 whereas it should be 4!
Output:
Before scf:
LDA+U parameters:
U( 1) = 4.00000000
alpha( 1) = 0.00000000
atom 8 Tr[ns(na)] (up, down, total) = 4.00000 0.00000 4.00000
spin 1
eigenvalues:
0.000 1.000 1.000 1.000 1.000
eigenvectors:
1.000 0.000 0.000 0.000 0.000
0.000 0.011 0.235 0.086 0.669
0.000 0.178 0.176 0.637 0.008
0.000 0.018 0.588 0.072 0.322
0.000 0.793 0.001 0.206 0.001
occupations:
0.000 -0.000 0.000 0.000 0.000
-0.000 1.000 0.000 0.000 0.000
0.000 0.000 1.000 -0.000 -0.000
0.000 0.000 -0.000 1.000 0.000
0.000 0.000 -0.000 0.000 1.000
spin 2
eigenvalues:
0.000 0.000 0.000 0.000 0.000
eigenvectors:
1.000 0.000 0.000 0.000 0.000
0.000 1.000 0.000 0.000 0.000
0.000 0.000 1.000 0.000 0.000
0.000 0.000 0.000 1.000 0.000
0.000 0.000 0.000 0.000 1.000
occupations:
0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000
atomic mag. moment = 4.000000
N of occupied +U levels = 4.000000
After scf:
LDA+U parameters:
U( 1) = 4.00000000
alpha( 1) = 0.00000000
atom 8 Tr[ns(na)] (up, down, total) = 3.57808 1.74127 5.31935
spin 1
eigenvalues:
0.503 0.503 0.802 0.885 0.885
eigenvectors:
0.000 0.000 1.000 0.000 0.000
0.068 0.489 0.000 0.047 0.397
0.489 0.068 0.000 0.397 0.047
0.080 0.364 0.000 0.090 0.466
0.364 0.080 0.000 0.466 0.090
occupations:
0.802 -0.000 -0.000 -0.000 -0.000
-0.000 0.673 -0.000 -0.189 -0.016
-0.000 -0.000 0.673 -0.016 0.189
-0.000 -0.189 -0.016 0.715 0.000
-0.000 -0.016 0.189 0.000 0.715
spin 2
eigenvalues:
0.266 0.266 0.271 0.469 0.469
eigenvectors:
0.000 0.000 1.000 0.000 0.000
0.047 0.467 0.000 0.055 0.432
0.467 0.047 0.000 0.432 0.055
0.079 0.408 0.000 0.097 0.416
0.408 0.079 0.000 0.416 0.097
occupations:
0.271 -0.000 -0.000 -0.000 -0.000
-0.000 0.365 -0.000 0.101 0.011
-0.000 -0.000 0.365 0.011 -0.101
-0.000 0.101 0.011 0.370 0.000
-0.000 0.011 -0.101 0.000 0.370
atomic mag. moment = 1.836805
N of occupied +U levels = 5.319347
When I plot the band structure, the overall valence and conduction bands do not
look bad (although not similar), and I see three dispersion less bands in the
gap!
I am very confused. I tried larger U values but it does not help. I also tried
scf after doing vc-relax, but I get the same results. I tried larger ecuts and
kpoints, but still the same thing happens.
I appreciate any comments or suggestions.
Best regards;
Mona Asadi Namin
Graduate student
Center for simulational physics
University of Georgia
--------------------------------------
Email:mon...@uga.ed<mailto:mon...@uga.edu>u<mailto:mon...@uga.edu>
Phone: +1-215-906-23-92
pw-manual-occupations.in
Description: pw-manual-occupations.in
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