[Wien] Fwd: Re: Fermi surface not 4 fold symmetric for a cubic material with space group Pm3m
Peter Blaha
pblaha at theochem.tuwien.ac.at
Thu Nov 8 21:51:16 CET 2018
What means:
Actually I have not shifted the k-mesh for the calculations ???
If you generated the k-mesh using initso, it will automatically shift it
!!! (The newest version gives you a warning).
How did you generate the k-mesh for the SO calculation ??
PS: Of course, the splitting of the 2 B atoms does not make the +X and
+X direction inequivalent.
Your system has inversion, and thus even when timeinversion is broken by
SO, +kx and -kx will give the same eigenvalues. And with (001)
magnetization, you get a tetragonal symmetry, thus (100) and (010)
directions are still identical. However, (001) could be different !!!
However, with zero magnetization (runsp_c) also the 001 direction
remains identical to the others.
PS: I'm not 100% sure that runsp_c -so works in an old wien2k version ..
-------- Weitergeleitete Nachricht --------
Betreff: Re: [Wien] Fermi surface not 4 fold symmetric for a cubic
material with space group Pm3m
Datum: Thu, 8 Nov 2018 23:00:10 +0530
Von: Anup Shakya <npshakya31 at gmail.com>
An: pblaha at theochem.tuwien.ac.at
Dear Prof. Blaha,
First of all thank you very much for taking out time from your busy
schedule to look at my problem.
As mentioned before, your wien2k version might be too old. But it could
be that you are lucky in this case.
Yes sir the Wien2k that I am using is an old version. But still
calculations without U and with SOC matched with all previous reported
calculations. Can't i trust the output of old version Wien2k?
In any case, I'd recommend to switch-off the RLOs, although I get very
similar results with/without RLOs
I have tried this and the changes are very little though for further
calculations I will not use RLOs as suggested by you.
fermi surface: By default, wien2k will create a shifted k-mesh. If I use
this shifted mesh, I also "see" an asymmetry in the fermi surface (but
ONLY there !)
x kgen -so and unshifted mesh solves this.
Actually I have not shifted the k-mesh for the calculations.
fermi surface with spin-orbit coupling: Do you know that you have to
copy case.outputso to case.output1up BEFORE you call xcrysden ???
(And of course, you must NOT do all the initial steps in xcd, only the
render steps. (If you are plotting band 15, you are making an error.
At first I have done
x lapw1 -up
x lapw1 -dn
x lapwso -orb -up
cp case.outputso file to case.output1up file
x lapw2 -so -fermi -up and then opened xcrysden, taken the fermi value
from grep :FER *.scf
and then plotted the Fermi surface.
Last but not least:
With my lousy parameters (500k, rkmax=6, U=0.32Ry) I got an INSULATOR,
when SO is switched on !!
:GAP (global) : 0.007693 Ry = 0.105 eV (accurate value if proper
k-mesh)
:GAP (this spin): 0.007693 Ry = 0.105 eV (accurate value if proper
k-mesh)
Sir, the problem is not only with the Fermi surface. The Fermi surface
matches exactly with the band structure (BS) calculations. The BS itself
is an-isotropic along the different G-X directions. Is it not because of
the application of SOC ? because the equivalent B atoms with
multiplicity 6 has now become two in-equivalent atoms with the
application of SOC. In this case also does one expect the same BS as in
the case where the B atoms were equivalent???
Further I have attached some figures in this e-mail. As you can see from
the DOS plots the material has some DOS at the EF indicating that it
should have some bands which cross the EF, which is validated from the
BS plots also. The calculations have been performed for U = 7 eV and J
=0. 83 eV, where the DOS is in close agreement with the XPS spectra.
I have attached the K-direction.jpg in this e-mail. What I meant to say
is when I said the Fermi surface is not the same along different
directions,it means the BS is also not the same along the different
directions. In the Figure denoted as 1 when the BS is plotted along the
direction X-G-X it is symmetric. Also the band structure along X-G-X in
Figure denoted as 2 is symmetric. But the band structure obtained along
the direction in Fig. 1 doesn't match with the BS along direction in
Fig.2. So, the problem is not only with the FS, the anisotropy can be
seen from the BS plots also.
So my question is when the structure itself has changed due to SOC,
does one expect the isotropy which was there when the structure didn't
change and why?
Before without the application of SOC the structure was cubic with 48
symmetry opertaions. After the application of SOC the structure is still
cubic Pm3m but with reduced i.e, 16 symmetry opertaions. In this case
also can one expect isotropic BS along different directions???
Further as you can clearly see from the plots that I have got some DOS
at the EF indicating the metallic behavior contradicting the insulating
behavior you have obtained. Can't I not trust the calculations at all in
old versions??
In the mean time I will try to upgrade the version which may take some
time and do the calculations.
I know I may be giving a lot of problems to you but I had no other
expert person to discuss with. I hope you will shed some light with your
expertise. Looking forward to hearing from you and sorry once again for
bothering you.
Sincerely,
Anup Pradhan Sakhya
On Thu, Nov 8, 2018 at 6:40 PM Peter Blaha <pblaha at theochem.tuwien.ac.at
<mailto:pblaha at theochem.tuwien.ac.at>> wrote:
Several possibilities:
As mentioned before, your wien2k version might be too old. But it could
be that you are lucky in this case.
In any case, I'd recommend to switch-off the RLOs, although I get very
similar results with/without RLOs
fermi surface: By default, wien2k will create a shifted k-mesh. If I
use
this shifted mesh, I also "see" an asymmetry in the fermi surface (but
ONLY there !)
x kgen -so and unshifted mesh solves this.
fermi surface with spin-orbit coupling: Do you know that you have to
copy case.outputso to case.output1up BEFORE you call xcrysden ???
(And of course, you must NOT do all the initial steps in xcd, only the
render steps. (If you are plotting band 15, you are making an error.
Last but not least:
With my lousy parameters (500k, rkmax=6, U=0.32Ry) I got an INSULATOR,
when SO is switched on !!
:GAP (global) : 0.007693 Ry = 0.105 eV (accurate value if proper
k-mesh)
:GAP (this spin): 0.007693 Ry = 0.105 eV (accurate value if proper
k-mesh)
Bandranges (emin - emax) and occupancy:
:BAN00024: 24 0.372850 0.544979 1.00000000
:BAN00025: 25 0.415238 0.544979 1.00000000
:BAN00026: 26 0.415238 0.544979 1.00000000
:BAN00027: 27 0.422669 0.557638 1.00000000
:BAN00028: 28 0.422669 0.557638 1.00000000
:BAN00029: 29 0.563325 0.609732 1.00000000
:BAN00030: 30 0.563325 0.609732 1.00000000
:BAN00031: 31 0.615807 0.620985 1.00000000
:BAN00032: 32 0.615807 0.620985 1.00000000
:BAN00033: 33 0.615811 0.626284 1.00000000
:BAN00034: 34 0.615811 0.626284 1.00000000
:BAN00035: 35 0.633977 0.907887 0.00000000
:BAN00036: 36 0.633977 0.907887 0.00000000
:BAN00037: 37 0.766409 0.932785 0.00000000
Maybe this will change with better parameters, but I suggest you check
all points mentioned above.
On 11/8/18 10:45 AM, Anup Shakya wrote:
> Dear Prof. Blaha,
>
> I have used the following structure file for non-magnetic
calculations
> with U and J. The U and J was used for the Sm atom and the
calculations
> were fine. I performed the calculations using runsp_c_lapw -orb -p.
>
> Title
> P LATTICE,NONEQUIV.ATOMS: 2 221 Pm-3m
> MODE OF CALC=RELA unit=ang
> 7.812131 7.812131 7.812131 90.000000 90.000000 90.000000
> ATOM 1: X=0.00000000 Y=0.00000000 Z=0.00000000
> MULT= 1 ISPLIT= 2
> Sm1 NPT= 781 R0=0.00001000 RMT= 2.50000 Z: 62.0
> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
> 0.0000000 1.0000000 0.0000000
> 0.0000000 0.0000000 1.0000000
> ATOM -2: X=0.20700000 Y=0.50000000 Z=0.50000000
> MULT= 6 ISPLIT=-2
> -2: X=0.79300000 Y=0.50000000 Z=0.50000000
> -2: X=0.50000000 Y=0.20700000 Z=0.50000000
> -2: X=0.50000000 Y=0.79300000 Z=0.50000000
> -2: X=0.50000000 Y=0.50000000 Z=0.20700000
> -2: X=0.50000000 Y=0.50000000 Z=0.79300000
> B 1 NPT= 781 R0=0.00010000 RMT= 1.61 Z: 5.0
> LOCAL ROT MATRIX: 0.0000000 0.0000000 1.0000000
> 0.0000000 1.0000000 0.0000000
> -1.0000000 0.0000000 0.0000000
> 48 NUMBER OF SYMMETRY OPERATIONS
>
> After this I performed GGA+SOC+U calculations. The direction of
> magnetization is chosen along 001. (Even if I change the
direction of
> magnetization to 010 or 100 the structure files looks the same as
below).
>
> Title s-o calc. M|| 0.00
0.00 1.00
> P 3 221
> RELA
> 7.812131 7.812131 7.812131 90.000000 90.000000 90.000000
> ATOM -1: X=0.00000000 Y=0.00000000 Z=0.00000000
> MULT= 1 ISPLIT=-2
> Sm1 NPT= 781 R0=.000010000 RMT= 2.50000 Z: 62.00000
> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
> 0.0000000 1.0000000 0.0000000
> 0.0000000 0.0000000 1.0000000
> ATOM -2: X=0.20700000 Y=0.50000000 Z=0.50000000
> MULT= 4 ISPLIT= 8
> -2: X=0.79300000 Y=0.50000000 Z=0.50000000
> -2: X=0.50000000 Y=0.20700000 Z=0.50000000
> -2: X=0.50000000 Y=0.79300000 Z=0.50000000
> B 1 NPT= 781 R0=.000100000 RMT= 1.61000 Z: 5.00000
> LOCAL ROT MATRIX: 0.0000000 0.0000000 1.0000000
> 0.0000000 1.0000000 0.0000000
> -1.0000000 0.0000000 0.0000000
> ATOM -3: X=0.50000000 Y=0.50000000 Z=0.20700000
> MULT= 2 ISPLIT=-2
> -3: X=0.50000000 Y=0.50000000 Z=0.79300000
> B 1 NPT= 781 R0=.000100000 RMT= 1.61000 Z: 5.00000
> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
> 0.0000000 1.0000000 0.0000000
> 0.0000000 0.0000000 1.0000000
> 16 NUMBER OF SYMMETRY OPERATIONS
> 1 0 0 0.0000000
> 0 1 0 0.0000000
> 0 0 1 0.0000000
> The command that I used is
> initso_lapw
> Magnetization direction 0 0 1, Emax default 5 Ryd
> -->Add RLO for NONE, ALL, CHOOSE elements? (N/a/c) : c
> p-Energy parameters for Sm1 atom is :
> 1 -1.58 0.002 CONT 1
> 1 0.30 0.000 CONT 1
> No RLO chosen for B atom
> In spinpolarized case SO may reduce symmetry.
> The program symmetso dedects the proper symmetry and creates new
struct
> and input files. (Note, equivalent atoms could become
inequivalent in
> some cases).
> Do you have a spinpolarized case (and want to run symmetso) ? (y/N)y
> 90.0000000000000 90.0000000000000
1.57079632679490 T
> 1.00000000000000 0.000000000000000E+000
0.000000000000000E+000
> 6.123233995736766E-017 1.00000000000000
0.000000000000000E+000
> 6.123233995736766E-017 6.123233995736766E-017 1.00000000000000
> 0.1u 0.0s 0:00.27 74.0% 0+0k 2232+4776io 6pf+0w
> emacs: Command not found.
> A new structure for SO calculations has been created (_so).
> If you commit it will create new smb6UJ7eV.struct, in1(c),
in2c, inc,
> clmsum/up/dn, vspup/dn and vnsup/dn files. (Please SAVE any
previous
> calculations)
> NOTE: Files for -orb (smb6UJ7eV.indm(c),inorb,dmatup/dn) must be
adapted
> manually
> Do you want to use the new structure for SO calculations ? (y/N)y
> We run KGEN to generate a new kmesh for the SO calculation:
> Number of Kpoint in smb6UJ7eV.klist is : 1000
> Spinorbit is now ready to run.
> Then I used the following command:
> runsp_c_lapw -so -orb -p.
>
> If you need any more information, then please let me know. Looking
> forward to hearing from you.
>
> Sincerely,
> Anup Pradhan Sakhya (Ph.D.)
> Visiting Post-Doctoral Fellow
> DCMP&MS, TIFR, Mumbai
>
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--
P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at
<mailto:blaha at theochem.tuwien.ac.at> WIEN2k: http://www.wien2k.at
WWW: http://www.imc.tuwien.ac.at/TC_Blaha
--------------------------------------------------------------------------
--
Anup Pradhan Sakhya (Ph.D.)
Visiting Post-Doctoral Fellow
DCMP&MS, TIFR, Mumbai
Alternative Email:anup.sakhya at tifr.res.in <mailto:rajib.mondal at tifr.res.in>
Contact No.: +91-8334841317/+91-8777838979
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