Actually, your input file for the conventionnal cell is wrong:
xred
0.0 0.0 0.0
1/4 1/4 1/4
1/2 1/2 0.0
0.0 1/2 1/2
1/2 0.0 1/2
3/4 3/4 1/4
1/4 3/4 3/4
3/4 1/2 3/4
1/2 in the last line should be 1/4
Then what does it give?
Emmanuel
Jedo a écrit :
4B0ADA0B.7080609@umich.edu" type="cite">Hi there,
Hmm.. If I'm understanding this right, whatever the cell size is, the
band structure at the Gamma point, (0 0 0) should be the same right?
For primitive cell, I have the following points for band structure at
(0 0 0)
kpt# 21, nband= 16, wtk= 1.00000, kpt= 0.0000 0.0000 0.0000
(reduced coord)
-6.19323 5.85746 5.85746 5.85746 8.37713 8.37713 8.37713
9.00292
13.48225 13.60932 13.60932 16.99403 16.99403 16.99403 20.87852
28.80835
For conventional cell, I have the following
kpt# 21, nband= 32, wtk= 1.00000, kpt= 0.0000 0.0000 0.0000
(reduced coord)
-6.16413 -1.94700 -1.94697 -1.94688 -1.94662 -1.94648 -1.94640
3.03807
3.03808 3.03813 3.03826 3.03833 3.03833 5.94579 5.94595
5.94612
6.51126 6.51137 6.51168 6.51184 6.51207 6.51211 8.46920
8.46929
8.46939 9.18951 13.60797 13.70326 13.70326 16.00834 16.00841
16.00857
I have included more bands.
However, the primitive cell band gap is between 5.85746 eV and 8.37713
eV. There are no bands between them. But for conventional cell, I have
6.51126 eV band between the two band gap. Is this normal when I use the
conventional cell?
Thanks.
Jedo
Emmanuel Arras wrote:
Pardon my naive question, but have you
"folded" your results? That is, band structure performed on a bigger
cell than the primitive one will have more bands in a smaller BZ. So,
if you want to compare the results with the primitive cell, you have to
"fold" them.
hopping I made myself clear...
Emmanuel
ธนูสิทธิ์ บุรินทร์ประโคน a écrit :
Dear all
I have in mind the same question as Jedo's.
I think the initail results of band calculations would look different
between the primitive cell and the conventional cell. This is because
the two cells have the Brillouin zones of different sizes and shapes so
that the k-points sampling used in the band calculation are different.
However, since we perform the band calculation for the same crystal,
both results should lead to identical intepretation. The problem is
how? Is there other points I am missing?
All comments or suggestions will be greatly appreciated.
Regards,
Thanusit Burinprakhon
*/On November 23, 2009 10:39:13 AM ICT, "Jedo"
<jedokim@umich.edu> wrote:/*
Hi all,
I am trying to compare if I get the same result for primitive
cells and
conventional cell when performing the electronic band structure
calculation. I may be totally wrong because I am just starting the
calculation. I am using two different structures, one for
conventional
cell and one for primitive cell. Shouldn't the following
structure give
me the same results? Not sure why I'm getting a totally different
band
structures. Please let me know if I'm just stupid. :) Thanks!!
Primitive cell
#Definition of the unit cell
-> acell 3*10.217 # This is equivalent to 10.217 10.217 10.217
-> rprim 0.0 0.5 0.5 # FCC primitive vectors (to be scaled by
acell)
-> 0.5 0.0 0.5
-> 0.5 0.5 0.0
->
-> #Definition of the atom types
-> ntypat 1 # There is only one type of atom
-> znucl 14 # The keyword "znucl" refers to the atomic number of
the
-> # possible type(s) of atom. The pseudopotential(s)
-> # mentioned in the "files" file must correspond
-> # to the type(s) of atom. Here, the only type is
-> Silicon.
->
->
-> #Definition of the atoms
-> natom 2 # There are two atoms
-> typat 1 1 # They both are of type 1, that is, Silicon.
-> xred # This keyword indicate that the location of the atoms
-> # will follow, one triplet of number for each atom
-> 0.0 0.0 0.0 # Triplet giving the REDUCED coordinate of atom
1.
-> 1/4 1/4 1/4 # Triplet giving the REDUCED coordinate of atom
2.
Conventional Cell
#Definition of the unit cell
acell 3*10.217 # This is equivalent to 10.18 10.18 10.18
rprim 1.0 0.0 0.0 # FCC primitive vectors (to be scaled by acell)
0.0 1.0 0.0
0.0 0.0 1.0
#Definition of the atom types
ntypat 1 # There is only one type of atom
znucl 14 # The keyword "znucl" refers to the atomic number of the
# possible type(s) of atom. The pseudopotential(s)
# mentioned in the "files" file must correspond
# to the type(s) of atom. Here, the only type is Silicon.
#Definition of the atoms
natom 8 # There are two atoms
typat 1 1 1 1 1 1 1 1 # They both are of type 1, that is, Silicon.
xred # This keyword indicate that the location of the atoms
# will follow, one triplet of number for each atom
0.0 0.0 0.0
1/4 1/4 1/4
1/2 1/2 0.0
0.0 1/2 1/2
1/2 0.0 1/2
3/4 3/4 1/4
1/4 3/4 3/4
3/4 1/2 3/4
-- ================================
Jedo Kim,
Heat Transfer Physics Laboratory
2350 Hayward, 2186 GG Brown Bldg.
University of Michigan, Ann Arbor, MI 48109-2143
Email: jedokim@umich.edu, jdzbox@hotmail.com
Tel: 734-764-3487 (o); 734-276-8370 (cell)
================================
--
Emmanuel ARRAS
L_Sim (Laboratoire de Simulation Atomistique)
SP2M / INAC
CEA Grenoble
tel : 00 33 (0)4 387 86862
--
Emmanuel ARRAS
L_Sim (Laboratoire de Simulation Atomistique)
SP2M / INAC
CEA Grenoble
tel : 00 33 (0)4 387 86862
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