Dear Prof Blaha,
With reference to the paper
Calculation of the lattice constant of solids with semilocal functionals
Philipp Haas, Fabien Tran, and Peter Blaha
PHYSICAL REVIEW B79, 085104 2009
For layred metal dichalcogenides (e. g. WS2), does it sound correct if the
difference between the lattice constants obtained by LDA and that obtained
GGA is equivalent to the lattice contraction due to van der Waals forces?
Osama
Department of Physics, Faculty of Science
Taibah University, A-Madinah Al-Munawarh, K. Saudi Arabia
A man would do nothing if he waited until he could do it so well that no one
could find fault.
On Sat, Mar 7, 2015 at 10:24 AM, Peter Blaha <pbl...@theochem.tuwien.ac.at>
wrote:
There is a misunderstanding: No, don't take a "mean" energy.
Check also the corresponding charge. When it is large, it is a
major
component and needs an energy parameter close to this energy.
In case.scf2 you can find under the line
:EPH and :EPL
the "mean" energy of the P-s states. If
they are not close to -0.73
(thats where you expand P-s), change the
corresponding input value.
For P-s, :EPL and :EPH are -1.34 and -0.43, mean of
-0.89, fairly close to
-0.73?
Together with the large P-s charge in :EPL it tells you, that
you should
lower the P-s parameter in case.in1 to -1.34
Whether one sets in addition a second l=0 Eparameter in case.in1
depends on
the E-separation between these EPL and EPH values, corresponding
charges
and the sphere radii (the larger the spheres: more probably
yes).
Here you have 0.9 Ry difference, but presumably the P-s charge
in the upper E-window is
very small and you have a very small spheres. Setting the two
energies to those values might lead to ghostbands and at least
at the beginning you
moved one E-parameter up to +6 Ry. As I said previously, you may
test it at the end
and set the second Al-s line to 0.30 (no search), so that the
actual E-parameter will be EF+0.2
Other than P-s they are not close. Al-s has -7.24,
-0.34, mean of -3.79,
case.in1 has -7.65.
O-s has -1.21, -0.30, mean is -0.75, while case.in1
has -1.46. Similarly
for Al-p and P-p.
Again, there should be l=0 E-parameters close to -7.24 and 1.21,
respectively.
In addition there should be definitely a second Al-s line at
0.30, since there are
"real" Al 3s states in the valence region.
I had mostly read about a supercell with one full
core hole. Some of these
are certainly cells where I do not want to build a
larger supercell than I
have to. Is the HALF a core hole a better choice?
Are you interested in XPS or in XAS. This is a VERY different
process where the
excited electron leave the bulk or stays whithin the bulk.
For XPS you are interested just in ONE number (Al-2p
ionizationpotential) and
Slaters transition state concept with half a core hole applies.
For XAS you want to simulate a spectrum for a system with one
core hole and an additional e- in
the valence band. Use (at least for insulators) a full core
hole.
Do I understand correctly that whether I use a HALF
core-hole or a full one,
I then do minimization of the ionic positions again?
No. Electronic spectroscopy is a very fast process and the ions
have no time to move
around.
The user-guide says "The energy cut-off specified in
lstart during init lapw
(usually -6.0 Ry) defines the separation
into core- and band-states (the latter contain both,
semicore and valence)."
How do I get the Al 2p state into the core?
Do I have to change the cut-off and use .lcore, or
is there some way to move
just the Al 2p state into the core?
Besides an Energy (-X Ry), you can also specify a charge
localization criterium
(like 0.999), which will put all states with less charge inside
sphere as valence.
Checkout case.outputst to see how much charge each state has
inside sphere:
E-up(Ry) E-dn(Ry) Occupancy q/sphere
core-state
1S -3.801989 -3.785331 1.00 1.00 0.9922 F
2S -0.236724 -0.003329 1.00 0.00 0.0675 F
PS There was no "reply" button in the archive except
"Reply via email". I
could not find an answer as to how to reply to a
post in either the Mail
Archive FAQ, or the WIEN mail archive.
Thanks,
David
---------------------------------------------------------------------------
At Thu, 05 Mar 2015 22:41:38 -0800, Peter Blaha
wrote
I think you have solved the problem very well.
Due to the small P sphere and the fact, that P-s
states are relatively
high in energy, the two linearization energies must
be quite well
separated. (An alternative would have been to simply
remove the second
l=0 line for P and change to "3" lines only:
0.30 3 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
1 0.30 0.000 CONT 1
1 -8.83 0.001 STOP 1
0 -0.73 0.002 CONT 1
Two more checks towards the "end of the scf cycle":
In case.scf2 you can find under the line :EPH and
:EPL
the "mean" energy of the P-s states. If they are not
close to -0.73
(thats where you expand P-s), change the
corresponding input value.
If the energy of the P-s states has gone down in
energy at the end of the
scf-cycles, you may
checkout if you can go down with this second E-s
input line from +6 back to
2.0
or even
back to 0.3 (sometimes such problems are
temporary).
PS: If you are interested in Al-2p XPS you should do
Slaters transition
state !
Put Al 2p into the core and introduce HALF a core
hole (compensated by a
background).
This gives much better core-eigenvalues that the
plain DFT groundstate
eigenvalues,
typically lt. 1 % error as compared to 10 % error in
comparison with
experiment.
In addition, final state screening effects are
better accounted for.
Am 06.03.2015 um 00:44 schrieb David Olmsted:
Ghostbands: pushed energy range in case.in1 to 6.3,
does this mean there is
a problem?
WIEN2k_14.2 (Release 15/10/2014)
Quad-Core AMD Opteron(tm) Processor 2378
Linux cluster
Intel 11.1 compilers with mkl.
The purpose of my computation is to compare
predicted XPS spectra for Al 2p
electon
for different environments of the Al atom in the
Al-P-O-H system.
User: beginner! My first time using WEIN2k.
Moderate amount of VASP work.
Issue: ghostbands
GGA-PBE, 48 atoms, K-mesh 6x6x4, no shift. Not
spin-polarized.
Initial cell and positions from relaxed GGA-PBE
using VASP, same K-mesh.
RMT from w2web StructGen (3% reduction)
H 0.63
O 1.17
P 1.34
Al 1.72
RKmax 3.5 to get "effective RKmax" of 6.5 for O.
rmt(min)*kmax = 3.50000
gmin = 11.11111
gmax = 20.00000
------- metavar_v.in0
TOT XC_PBE
(XC_LDA,XC_PBESOL,XC_WC,XC_MBJ,XC_REVTPSS)
NR2V IFFT (R2V)
64 120 108 1.00 1 min IFFT-parameters,
enhancement factor, iprint
---------
For default -6 Ry cutoff for core states, charge was
leaking out of RMT
sphere
for P 2p states. Final iteration in
metavar_v.outputst:
14 350
14 1.85E-07 1.884765E+00 -8.645384E-01
-8.645386E-01 1.72E-07
-1.67E-08 1.707034E-01 1.707034E-01
1S -153.17082 -153.17082
2S -12.78682 -12.78682
2P* -9.19366 -9.19366
2P -9.12626 -9.12626
3S -1.02668 -1.02668
3P* -0.40735 -0.40735
3P -0.40342 -0.40342
Cutoff set to -9.2 Ry. (Also tried leaving it at
-6.0 Ry and touching
.lcore. Similar results.)
===============================================================
---------------------------- Question
-------------------------
===============================================================
With the original case.in1 file, had messages for
the P atom, L=0:
(All these messages are from the first run of
LAPW2.)
metavar_v.scf2_1: QTL-B VALUE .EQ. 4951.54243 in
Band of energy -6.46139
ATOM= 2 L= 0
increased 0.3 to 2.3 in case.in1, now:
QTL-B VALUE .EQ. 1347.97207 in Band of energy
-4.71553 ATOM= 2 L=
0
increased it 4.3
QTL-B VALUE .EQ. 602.53449 in Band of energy
-2.14697 ATOM= 2 L=
0
When I increased it to 6.3, no complaints.
The initial scf run has completed with no warnings;
the position
minimization is still running.
In the mailing list search, there are suggestions to
increase the (upper)
energy range to
1.3 or "even 2.0" Ry. That makes me worry about the
fact that I had to
increase it to a much
larger value. Does this mean something is going
wrong?
------------------------- End of question
------------------------
=========== case.in1
=============================================
WFFIL EF=.1268392143 (WFFIL, WFPRI, ENFIL, SUPWF)
3.5 10 4 (R-MT*K-MAX; MAX L IN WF,
V-NMT
0.30 4 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
APW/LAPW)
0 0.30 0.000 CONT 1
0 -7.65 0.001 STOP 1
1 0.30 0.000 CONT 1
1 -4.81 0.001 STOP 1
0.30 4 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
APW/LAPW)
1 0.30 0.000 CONT 1
1 -8.83 0.001 STOP 1
0 -0.73 0.002 CONT 1
0 6.30 0.000 CONT 1
0.30 3 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
APW/LAPW)
0 -1.46 0.002 CONT 1
0 0.30 0.000 CONT 1
1 0.30 0.000 CONT 1
0.30 3 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
APW/LAPW)
0 -1.46 0.002 CONT 1
0 0.30 0.000 CONT 1
1 0.30 0.000 CONT 1
0.30 3 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
APW/LAPW)
0 -1.46 0.002 CONT 1
0 0.30 0.000 CONT 1
1 0.30 0.000 CONT 1
0.30 3 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
APW/LAPW)
0 -1.46 0.002 CONT 1
0 0.30 0.000 CONT 1
1 0.30 0.000 CONT 1
0.30 3 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
APW/LAPW)
0 -1.46 0.002 CONT 1
0 0.30 0.000 CONT 1
1 0.30 0.000 CONT 1
0.30 3 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
APW/LAPW)
0 -1.46 0.002 CONT 1
0 0.30 0.000 CONT 1
1 0.30 0.000 CONT 1
0.30 1 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
APW/LAPW)
0 0.30 0.000 CONT 1
0.30 1 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
APW/LAPW)
0 0.30 0.000 CONT 1
0.30 1 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
APW/LAPW)
0 0.30 0.000 CONT 1
0.30 1 0 (GLOBAL E-PARAMETER WITH n
OTHER CHOICES, global
APW/LAPW)
0 0.30 0.000 CONT 1
K-VECTORS FROM UNIT:4 -12.2 1.5 250 emin
/ de (emax=Ef+de) /
nband #red
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--
-----------------------------------------
Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pbl...@theochem.tuwien.ac.at
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