Re: [Wien] crystal field splitting

2015-08-24 Thread Lan, Wangwei
Dear professor Vñictor Luaña:

Thanks very much for your kindly reply. Your reply is really helpful and I will 
go on studying in this field. Thanks again.

Sincerely
Wangwei Lan


From: wien-boun...@zeus.theochem.tuwien.ac.at 
wien-boun...@zeus.theochem.tuwien.ac.at on behalf of Víctor Luaña Cabal 
vic...@fluor.quimica.uniovi.es
Sent: Sunday, August 23, 2015 15:37
To: A Mailing list for WIEN2k users
Cc: Victor Luaña
Subject: Re: [Wien] crystal field splitting

On Sun, Aug 23, 2015 at 07:51:33PM +, Lan, Wangwei wrote:
 Dear Wien2k user:


 I am very new in WIEN2k. Now I am running case on our crystal system
 which contains a transition metal Cr. I am particularly interested in
 the d orbital splitting, the energy levels of 5 d orbitals. Does anyone
 know how to calculate the orbital splitting using WIEN2k?

Wangwei,

The answer is not simple and there can be more than one opinion living
around. Let me express mu 0.02 euros.

Crystal field splitting parameters (delta-D, i.e. t2g-eg splitting, Racah
parameters, etc) is by fitting a model to the theoretical or experimental
true calculations of total energy diferences between correlated
electronic states. In other terms, there are no such a thing as
orbital splitting as a well defined element. The orbital approach is
a interpretative description, not a physical definition.

There are decades that I not contribute to this old subject and I
reccomend you to follow the more recent papers by Profs. Luis Seijo and
Zoila Barandiarán, from the UAM (Universidad Aotónoma de Madrid).
You will find in their work a good description of old and modern
treatments, laike MOLCAS calculations, relativity contributions, and
the huge importance of large correlation treatments. Both contribute
to the development of MOLCAS.

http://www.uam.es/personal_pdi/ciencias/lseijo/
http://www.uam.es/personal_pdi/ciencias/yara/

Notice that the field emerged from dealing with impurities within
crystals, so most of the evolution that I learned was releted to
the moleculartreatment of embedded impurities neighborhoods.

On a solid state perspective, and your mention of wannier functions
lets me thing you may prefer that, notice that d-d, d-s and d-p
transitions correspond to heavily correlated problems, and the wave
funcion perspective has a much longer tradition than TD-DFT ones,
but let me just say that I know less abiout them. The conferences
by  Stefano Baroni on the calculation of the color of natural dies
are simple awesome.

http://stefano.baroni.me/presentations.html

Best regards and good luck if you come new to this field,
Dr. Vñictor Luaña
--
 .  .In science a person can be convinced by a good argument.
/ `' \   That is almost impossible in politics or religion
   /(o)(o)\  (Adapted from Carl Sagan)
  /`. \/ .'\  Lo mediocre es peor que lo bueno, pero también es peor
 /   '`'`   \ que lo malo, porque la mediocridad no es un grado, es una
 |  \'`'`/  | actitud -- Jorge Wasenberg, 2015
 |  |'`'`|  | (Mediocre is worse than good, but it is also worse than
  \/`'`'`'\/  bad, because mediocrity is not a grade, it is an attitude)
===(((==)))==+=
! Dr.Víctor Luaña, in silico chemist  prof. ! I hate the bureaucracy
! Departamento de Química Física y Analítica ! imposed by companies to
! Universidad de Oviedo, 33006-Oviedo, Spain ! which I owe nothing:
! e-mail:   vic...@fluor.quimica.uniovi.es   ! amazon, ResearchGATE and
! phone: +34-985-103491  fax: +34-985-103125 ! the like.
++
 GroupPage : http://azufre.quimica.uniovi.es/
 (being reworked)
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[Wien] crystal field splitting

2015-08-23 Thread Lan, Wangwei
Dear Wien2k user:


I am very new in WIEN2k. Now I am running case on our crystal system which 
contains a transition metal Cr. I am particularly interested in the d orbital 
splitting, the energy levels of 5 d orbitals. Does anyone know how to calculate 
the orbital splitting using WIEN2k?


I'v read several papers, they use wannier90 to calculate the on site energy, 
then interpret that on site energy difference as crystal field splitting. 
However, when I apply this method, I got controversy  results as our group 
theory analysis. I seriously doubt about this kind of interpretation, hope you 
can help me. Thanks very much.




Sincerely

Wangwei Lan
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Re: [Wien] crystal field splitting

2015-08-23 Thread Víctor Luaña Cabal
On Sun, Aug 23, 2015 at 07:51:33PM +, Lan, Wangwei wrote:
 Dear Wien2k user:
 
 
 I am very new in WIEN2k. Now I am running case on our crystal system
 which contains a transition metal Cr. I am particularly interested in
 the d orbital splitting, the energy levels of 5 d orbitals. Does anyone
 know how to calculate the orbital splitting using WIEN2k?

Wangwei,

The answer is not simple and there can be more than one opinion living
around. Let me express mu 0.02 euros.

Crystal field splitting parameters (delta-D, i.e. t2g-eg splitting, Racah
parameters, etc) is by fitting a model to the theoretical or experimental
true calculations of total energy diferences between correlated
electronic states. In other terms, there are no such a thing as
orbital splitting as a well defined element. The orbital approach is
a interpretative description, not a physical definition.

There are decades that I not contribute to this old subject and I
reccomend you to follow the more recent papers by Profs. Luis Seijo and
Zoila Barandiarán, from the UAM (Universidad Aotónoma de Madrid).
You will find in their work a good description of old and modern
treatments, laike MOLCAS calculations, relativity contributions, and
the huge importance of large correlation treatments. Both contribute
to the development of MOLCAS.

http://www.uam.es/personal_pdi/ciencias/lseijo/
http://www.uam.es/personal_pdi/ciencias/yara/

Notice that the field emerged from dealing with impurities within
crystals, so most of the evolution that I learned was releted to
the moleculartreatment of embedded impurities neighborhoods.

On a solid state perspective, and your mention of wannier functions
lets me thing you may prefer that, notice that d-d, d-s and d-p
transitions correspond to heavily correlated problems, and the wave
funcion perspective has a much longer tradition than TD-DFT ones,
but let me just say that I know less abiout them. The conferences
by  Stefano Baroni on the calculation of the color of natural dies
are simple awesome.

http://stefano.baroni.me/presentations.html

Best regards and good luck if you come new to this field,
Dr. Vñictor Luaña
--
 .  .In science a person can be convinced by a good argument.
/ `' \   That is almost impossible in politics or religion
   /(o)(o)\  (Adapted from Carl Sagan)
  /`. \/ .'\  Lo mediocre es peor que lo bueno, pero también es peor
 /   '`'`   \ que lo malo, porque la mediocridad no es un grado, es una
 |  \'`'`/  | actitud -- Jorge Wasenberg, 2015
 |  |'`'`|  | (Mediocre is worse than good, but it is also worse than
  \/`'`'`'\/  bad, because mediocrity is not a grade, it is an attitude)
===(((==)))==+=
! Dr.Víctor Luaña, in silico chemist  prof. ! I hate the bureaucracy
! Departamento de Química Física y Analítica ! imposed by companies to
! Universidad de Oviedo, 33006-Oviedo, Spain ! which I owe nothing:
! e-mail:   vic...@fluor.quimica.uniovi.es   ! amazon, ResearchGATE and
! phone: +34-985-103491  fax: +34-985-103125 ! the like.
++
 GroupPage : http://azufre.quimica.uniovi.es/
 (being reworked)
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Re: [Wien] Crystal field splitting

2014-11-04 Thread pieper

Dear Salman,

unfortunately I have neither means (no Wien2k on my notebook) nor time 
right now to quickly provide an answer to your problems. Anyhow, 
directing you to literature you can cite is probably better than an 
elaborate email lecture on crystal field splittings (not being really an 
expert I am not the ideal person to give such a lecture anyway).


To me the best way to proceed seems to be be:

- get your hands on some textbook on magnetism with a chapter on crystal 
field effects. Kei Yosida: Theory of Magnetism, Springer Series in Solid 
State Science vol 122 might be one choice. Personally, when I ran into 
crystal field effects a rather long time ago, I liked the article of M. 
T. Hutchings: Point charge ... in F. Seitz, D. Turnbull, Solid State 
Physics, vol. 16, p. 227, Academic Press 1964.


- read (understand) that chapter. You should know at this stage which 
parameters appear in the crystal field Hamiltonian if you know L and the 
point symmetry. I did not use Pavel Novaks new package for Wien2k up to 
now but I expect that you can understand its I/O on that basis. And you 
should be aware of the limitations of the concept, especially in a 
3d-metal!


- Find the configuration of B nearest neighbors for the two 
non-equivalent Ni sites in your structure. The idea is that charges 
farther out are pretty much shielded. Simply look at the structure using 
Xcrysden or something similar to identify this configuration. In Wien2k, 
outputnn gives you the number and position of these B atoms. My guess (a 
guess, not more!) is, that one Ni site has a (distorted) octahedral 
configuration, the other a (also distorted) tetrahedral one. CF 
splitting usually is considered in steps of decreasing importance of the 
contribution in the Hamiltonian: first approximate the situation by a 
cubic crystal field, then take into account, say, tetragonal distortions 
of the ideal octahedron, and so on, lowering symmetry in each step.


I hope this helps,

Martin


---
Dr. Martin Pieper
Karl-Franzens University
Institute of Physics
Universitätsplatz 5
A-8010 Graz
Austria
Tel.: +43-(0)316-380-8564


Am 03.11.2014 13:41, schrieb Salman Zarrini:

+++
Dear Martin and Delamora,

Many thanks for your answer, actually, controversial state for me here
 is 3d orbitals of Ni elements crystalline together with boron in
a  orthorhombic structure, Pnma space group. I can see different kind
of  point group in case.outputsgroup(1,1,C1 for sort one, m,m,Cs for
atom  sort 2 and m,m,Cs for atom sort 3 and a mmm,2/m,2/m 2/m,D2h in
the  end for the whole structure)but I can not make a link between
them and  potential crystal filed splitting for this structure, for
convenience  the struct file has been enclosed, I would be thankful if
you guided  me to find the proper crystal filed.

Cheers,
Salman
+++



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Re: [Wien] Crystal field splitting

2014-11-03 Thread pieper

Dear Salman,

to be a little bit more precise, crystal field splitting is a local 
concept: The Coulomb interaction of all electrons in a given shell 
characterized by its angular momentum with the surrounding charge 
distribution is represented by a minimal set of angular momentum 
operators. To make sense this should to be a shell of reasonably well 
localized electrons (usually a 4f-shell). If you have a metal the 
bandwidth of that particular band should be small, the conduction 
electrons should be contributed by other shells.


It also means that it is NOT the overall crystal symmetry you have to 
consider, but the point symmetry group of the crystalografic site 
occupied by the (Rare Earth?) element you are interested in. When your 
structure has sites with, say, octahedral and tetrahedral symmetry the 
crystal field Hamiltonian (and its eigenvalues, the splitting) will 
reflect these symmetries. The point group symmetries are tabulated, e.g. 
for the Wyckoff positions at the Bilbao server 
(http://www.cryst.ehu.es/)


Best regards,

Martin


---
Dr. Martin Pieper
Karl-Franzens University
Institute of Physics
Universitätsplatz 5
A-8010 Graz
Austria
Tel.: +43-(0)316-380-8564


Am 03.11.2014 03:56, schrieb delamora:

The crystal field splitting depends on the crystal symmetry!!, but for
a compound with metallic characteristics the bandwidth will be larger
that the field splitting.

De: wien-boun...@zeus.theochem.tuwien.ac.at
wien-boun...@zeus.theochem.tuwien.ac.at en nombre de Salman Zarrini
salman.zarr...@tu-darmstadt.de
Enviado: domingo, 02 de noviembre de 2014 04:57 p.m.
Para: wien@zeus.theochem.tuwien.ac.at
Asunto: [Wien] Crystal field splitting

Dear Wien2k users,

I was wondering that how can I find out which kinds of crystal field
splitting (Octahedral, Tetrahedral, Pentagonal bipyramidal,...) have
been applied on my bulk metallic structure?

Best regards,

Salman

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Re: [Wien] Crystal field splitting

2014-11-03 Thread Salman Zarrini


+++
Dear Martin and Delamora,

Many thanks for your answer, actually, controversial state for me here  
is 3d orbitals of Ni elements crystalline together with boron in a  
orthorhombic structure, Pnma space group. I can see different kind of  
point group in case.outputsgroup(1,1,C1 for sort one, m,m,Cs for atom  
sort 2 and m,m,Cs for atom sort 3 and a mmm,2/m,2/m 2/m,D2h in the  
end for the whole structure)but I can not make a link between them and  
potential crystal filed splitting for this structure, for convenience  
the struct file has been enclosed, I would be thankful if you guided  
me to find the proper crystal filed.


Cheers,
Salman
+++


ni3b
P362_Pnma
 RELA
  9.85 12.494418  8.292604 90.00 90.00 90.00
ATOM  -1: X=0.18024000 Y=0.06237541 Z=0.15479748
  MULT= 8  ISPLIT= 8
  -1: X=0.81976000 Y=0.93762459 Z=0.84520252
  -1: X=0.68024000 Y=0.06237541 Z=0.34520252
  -1: X=0.31976000 Y=0.93762459 Z=0.65479748
  -1: X=0.31976000 Y=0.56237541 Z=0.65479748
  -1: X=0.68024000 Y=0.43762459 Z=0.34520252
  -1: X=0.81976000 Y=0.56237541 Z=0.84520252
  -1: X=0.18024000 Y=0.43762459 Z=0.15479748
Ni NPT=  781  R0=0.5000 RMT=2.1100   Z:  28.0
LOCAL ROT MATRIX:1.000 0.000 0.000
 0.000 1.000 0.000
 0.000 0.000 1.000
ATOM  -2: X=0.02795073 Y=0.2500 Z=0.63114648
  MULT= 4  ISPLIT= 8
  -2: X=0.97204927 Y=0.7500 Z=0.36885352
  -2: X=0.52795073 Y=0.2500 Z=0.86885352
  -2: X=0.47204927 Y=0.7500 Z=0.13114648
Ni NPT=  781  R0=0.5000 RMT=2.1100   Z:  28.0
LOCAL ROT MATRIX:0.000 1.000 0.000
 0.000 0.000 1.000
 1.000 0.000 0.000
ATOM  -3: X=0.38206182 Y=0.2500 Z=0.43792072
  MULT= 4  ISPLIT= 8
  -3: X=0.61793818 Y=0.7500 Z=0.56207928
  -3: X=0.88206182 Y=0.2500 Z=0.06207928
  -3: X=0.11793818 Y=0.7500 Z=0.93792072
B  NPT=  781  R0=0.0001 RMT=1.5600   Z:   5.0
LOCAL ROT MATRIX:0.000 1.000 0.000
 0.000 0.000 1.000
 1.000 0.000 0.000
   8  NUMBER OF SYMMETRY OPERATIONS
-1 0 0 0.
 0-1 0 0.
 0 0-1 0.
   1
 1 0 0 0.
 0 1 0 0.
 0 0 1 0.
   2
-1 0 0 0.5000
 0-1 0 0.
 0 0 1 0.5000
   3
-1 0 0 0.
 0 1 0 0.5000
 0 0-1 0.
   4
-1 0 0 0.5000
 0 1 0 0.5000
 0 0 1 0.5000
   5
 1 0 0 0.5000
 0-1 0 0.5000
 0 0-1 0.5000
   6
 1 0 0 0.
 0-1 0 0.5000
 0 0 1 0.
   7
 1 0 0 0.5000
 0 1 0 0.
 0 0-1 0.5000
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[Wien] Crystal field splitting

2014-11-02 Thread Salman Zarrini


Dear Wien2k users,

I was wondering that how can I find out which kinds of crystal field  
splitting (Octahedral, Tetrahedral, Pentagonal bipyramidal,...) have  
been applied on my bulk metallic structure?


Best regards,

Salman

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Re: [Wien] Crystal field splitting

2014-11-02 Thread delamora
The crystal field splitting depends on the crystal symmetry!!, but for a 
compound with metallic characteristics the bandwidth will be larger that the 
field splitting.

De: wien-boun...@zeus.theochem.tuwien.ac.at 
wien-boun...@zeus.theochem.tuwien.ac.at en nombre de Salman Zarrini 
salman.zarr...@tu-darmstadt.de
Enviado: domingo, 02 de noviembre de 2014 04:57 p.m.
Para: wien@zeus.theochem.tuwien.ac.at
Asunto: [Wien] Crystal field splitting

Dear Wien2k users,

I was wondering that how can I find out which kinds of crystal field
splitting (Octahedral, Tetrahedral, Pentagonal bipyramidal,...) have
been applied on my bulk metallic structure?

Best regards,

Salman

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[Wien] Crystal field splitting in empty 3d band of Fe2O3

2009-09-17 Thread Hua Wu
Dear Y. Ding,

 For the material Fe2O3 having the formal high-spin Fe3+ and a closed 
up-spin shell, I think LDA (when giving an insulating solution) or LDA+U
partial d-DOS can well show the t2g-eg (if being eigenorbitals) crystal field 
splitting. 

Just a note: have you worked with a hexagonal lattice coordinate or a local 
octahedral coordinate ?  May the short Fe-Fe pair or a trigonal field distort 
too much the crystal field level diagram ?

best regards -- H. Wu

On Thursday 17 September 2009 07:51, Pavel Novak wrote:
  Dear Yang Ding,

 yesterday I forgot third point, which perhaps could give answer to your
 question. If U is chosen such that it put d-states close to the oxygen p-
 states, hybridization increases and it shifts the d-levels down if EdEp,
 or up if EdEp.
 Regards Pavel

 On Wed, 16 Sep 2009, Pavel Novak wrote:
  Dear Yang Ding,
 
  care is needed when estimating the crystal field splitting from the LDA+U
  calculation using the DOS. There are two reasons for it. First, the LDA+U
  lower the energy of more occupied states and increase the energy of less
  occupied states. Even if the bands are above Fermi energy, they contain
  nonzero fraction of electrons (cf :QTL in scf file), which is different
  for eg and t2g states, hence LDA+U distorts the splitting. Second, the
  selfinteraction of the d-electrons is present, again distorting the
  crystal field splitting.
 
  Regards
  Pavel Novak
 
  On Tue, 15 Sep 2009, Yang Ding wrote:
   Dear WIEN2k  users,
  
   I am really new to WIEN2k, and wondering if you could give your advice
   and experience on following question concerning the crystal filed
   splitting calculated from WIEN2k.
  
   In order to understand if the pre-edge splitting appearing in the Fe
   K-edge spectra (1s-4p transition) measured by emission-XANES on Fe2O3
   [Groot et al. J. Phys.: Condens. Matter 21 (2009) 104207
   http://www.iop.org/EJ/abstract/0953-8984/21/10/104207/], is linked to
   crystal-filed splitting in 3d empty band. We did a very preliminary
   ground state calculation using WIEN2k based on GGA+U (and LSDA+U) with
   U = 4 eV structure to check the crystal field splitting in empty d band
   above Fermi level.
  
   As a result, we found that above 2-6 eV above Fermi level, the energy
   of t2g is higher than that of eg. This result is similar to what
   reported by Rollsman et al (PHYSICAL REVIEW B 69, 165107 (2004)
   http://prola.aps.org/abstract/PRB/v69/i16/e165107) on Fe2O3. In his
   calculation (GGA/LSDA+U , U= 4eV), the energy of t2g is also higher
   than that of eg. So my question is why the t2g and eg are reversed in
   DFT, but the Multiplet calculation gives contradictory results (i.e
   from Groot et al.).
  
   I noticed that  Glatzel et al (PHYSICAL REVIEW B 77, 115133 (2008)
   http://prola.aps.org/abstract/PRB/v69/i16/e165107) reported that they
   obtained the right crystal field splitting using (LDA+U, U=6 eV) from
   WIEN2k.   So we wonder if we might missed something in the
   calculations?
  
   Thanks  in advance for your help,



[Wien] Crystal field splitting in empty 3d band of Fe2O3

2009-09-16 Thread Pavel Novak
Dear Yang Ding,

care is needed when estimating the crystal field splitting from the LDA+U 
calculation using the DOS. There are two reasons for it. First, the LDA+U 
lower the energy of more occupied states and increase the energy of less 
occupied states. Even if the bands are above Fermi energy, they contain 
nonzero fraction of electrons (cf :QTL in scf file), which is different 
for eg and t2g states, hence LDA+U distorts the splitting. Second, the 
selfinteraction of the d-electrons is present, again distorting the 
crystal field splitting.

Regards
Pavel Novak

On Tue, 15 Sep 2009, Yang Ding wrote:

 Dear WIEN2k  users,
 
 I am really new to WIEN2k, and wondering if you could give your advice and
 experience on following question concerning the crystal filed splitting
 calculated from WIEN2k.
 
 In order to understand if the pre-edge splitting appearing in the Fe K-edge
 spectra (1s-4p transition) measured by emission-XANES on Fe2O3 [Groot et al.
 J. Phys.: Condens. Matter 21 (2009) 104207
 http://www.iop.org/EJ/abstract/0953-8984/21/10/104207/], is linked to
 crystal-filed splitting in 3d empty band. We did a very preliminary ground
 state calculation using WIEN2k based on GGA+U (and LSDA+U) with U = 4 eV
 structure to check the crystal field splitting in empty d band above Fermi
 level.
 
 As a result, we found that above 2-6 eV above Fermi level, the energy of t2g
 is higher than that of eg. This result is similar to what reported by Rollsman
 et al (PHYSICAL REVIEW B 69, 165107 (2004)
 http://prola.aps.org/abstract/PRB/v69/i16/e165107) on Fe2O3. In his
 calculation (GGA/LSDA+U , U= 4eV), the energy of t2g is also higher than that
 of eg. So my question is why the t2g and eg are reversed in DFT, but the
 Multiplet calculation gives contradictory results (i.e from Groot et al.).
 
 I noticed that  Glatzel et al (PHYSICAL REVIEW B 77, 115133 (2008)
 http://prola.aps.org/abstract/PRB/v69/i16/e165107) reported that they
 obtained the right crystal field splitting using (LDA+U, U=6 eV) from
 WIEN2k.   So we wonder if we might missed something in the calculations?
 
 Thanks  in advance for your help,
 

-- 


[Wien] Crystal field splitting in empty 3d band of Fe2O3

2009-09-15 Thread Yang Ding
Dear WIEN2k  users,

I am really new to WIEN2k, and wondering if you could give your advice 
and experience on following question concerning the crystal filed 
splitting calculated from WIEN2k.

In order to understand if the pre-edge splitting appearing in the Fe 
K-edge  spectra (1s-4p transition) measured by emission-XANES on Fe2O3 
[Groot et al. J. Phys.: Condens. Matter 21 (2009) 104207 
http://www.iop.org/EJ/abstract/0953-8984/21/10/104207/], is linked to 
crystal-filed splitting in 3d empty band. We did a very preliminary 
ground state calculation using WIEN2k based on GGA+U (and LSDA+U) with U 
= 4 eV structure to check the crystal field splitting in empty d band 
above Fermi level.

As a result, we found that above 2-6 eV above Fermi level, the energy of 
t2g is higher than that of eg. This result is similar to what reported 
by Rollsman et al (PHYSICAL REVIEW B 69, 165107 (2004) 
http://prola.aps.org/abstract/PRB/v69/i16/e165107) on Fe2O3. In his 
calculation (GGA/LSDA+U , U= 4eV), the energy of t2g is also higher than 
that of eg. So my question is why the t2g and eg are reversed in DFT, 
but the Multiplet calculation gives contradictory results (i.e from 
Groot et al.).

I noticed that  Glatzel et al (PHYSICAL REVIEW B 77, 115133 (2008) 
http://prola.aps.org/abstract/PRB/v69/i16/e165107) reported that they 
obtained the right crystal field splitting using (LDA+U, U=6 eV) from 
WIEN2k.   So we wonder if we might missed something in the calculations?

Thanks  in advance for your help,
-- 

Yang Ding 
http://www.aps.anl.gov/Users/Scientific_Interest_Groups/HPSynC/people/%7EYDing.html

Staff Scientist

RM-B3180/Blgd-401

HPSynC at Advanced Photon Source

Argonne National Laboratory

9700 S. Cass Avenue

Argonne, IL 60439

Phone: 630-252-6288

Email: yangding at aps.anl.gov

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