Dear wien2k users,
There is a possible (usually rather small) problem in all calculations
with orbital potentials (-orb -eece) in cases without inversion symmetry
and a k-mesh, which "adds" inversion symmetry.
(There should be no problems with self-consistent spin-orbit
calculations (-so),
But mixing is switched off in case.inorb !!
On 01/17/2018 09:54 AM, William Lafargue-dit-Hauret wrote:
Dear Prof. Blaha and Marks,
Thank you for your comments and suggestions.
Looking at the SRC_orb/main.f, orb seems to read potential files to mix
with old vorb files.
William
Le
Dear Prof. Blaha and Marks,
Thank you for your comments and suggestions.
Looking at the SRC_orb/main.f, orb seems to read potential files to mix
with old vorb files.
William
Le 17/01/2018 à 08:03, Peter Blaha a écrit :
Just a few comments:
In many posts to this topic I saw the -c
Just a few comments:
In many posts to this topic I saw the -c switch. This is not
necessary and prone to errors. Don't use -c . It will be done
automatically.
I think, the orb program reads case.dmat* files, and produces
case.vorb* files. It is not reading vorb files.
And it does
Dear Xavier,
The method you just used avoids time-reversal symmetry for -orb. My
intuition is that this is right, but I don't think I ever convinced
Peter of this. An alternative (that might be wrong) and avoids double
counting is:
Setup case.inso with NO spin-orbit on any atom, then do
Dear Peter and Laurence
Thank you for your replies. Using the following strategy it seems to
work nicely (preliminary results):
runsp_lapw -eece -p -ec 0.1 -NI
Then for larger EMAX and kmesh without SO we do :
x lapw1 -up -c -orb
x lapw1 -dn -c -orb
And for the different magnetization
Dear Profs. Blaha and Marks,
Thank you for your advices. I have a question regarding your comment on
the EECE case.
The resulting effective potential of LDA+U and EECE corrections is
decomposed in vorb files, but I don't understand why the spin-coupling
file case.vorbud shouldn't appear in
I was not clear Peter. I clarify the way we proceed.
We do runsp_lapw -eece -p -ec 0.1 -NI
Then for larger EMAX and kmesh without SO we do :
x lapw1 -up -c -orb
x lapw1 -dn -c -orb
And for the different magnetization directions we do:
x lapwso -c -up -orb
x lapw2 -so -up -c
x lapw2 -so
OK we will check it. In EECE we have no case.vorbud file (empty file).
Le 16/01/2018 à 16:58, Peter Blaha a écrit :
Hups: If this is true, you are counting the orbital potential twice !
-orb should only be present in the lapwso step.
(And in fact, the lapw1 steps need to be done just once for
Hups: If this is true, you are counting the orbital potential twice !
-orb should only be present in the lapwso step.
(And in fact, the lapw1 steps need to be done just once for the
increased k-mesh; but not when changing the M-direction in case.inso)
Please check the presence of case.vorbud.
Dear Peter
You are totally correct. We are doing SO non-selfconsistent by using a
standard procedure for EECE calculations:
runsp_lapw -eece -p -ec 0.1 -NI
and then we estimate the MAE using this non-SCF procedure :
Increase EMAX in case.in1c - increase kmesh if needed
x lapw1 -up
Hallo Xavier,
Looks rather strange.
Eventually I would have expected problems both, in 16.1 and 17.1 (but
not 14.2) due to the off-diagonal density matrices. But this should
concern ONLY LDA+U, not -eece.
Just to be sure:
I expect you do SO non-selfconsistent, so vorbup/dn(du) files are
Dear Xavier,
One other suggestion, with a caveat. In general if the physical model
is weak/wrong or there are coding errors, the convergence is poor.
This has to do with what I call "noise" in the calculation (for want
of a better term). Since the mixing is implicitly a Simplex derivative
noise
Dear Laurence
Here is the point. Our results show that in version 17 a problem occurs
related to the time-reversal, which appears only if we do GGA+U or EECE.
a) The calculations we showed are already done in P1. Indeed, I wanted
to avoid any problems related to symmetry.
b) we (me and my
I may annoy Peter with the comment below, so it goes
Personally I have some reservations about the consistency between the
orbital potential and time-reversal operations in -so. Three possible
tests:
a) Reduce the symmetry to P1 and run. While this is slower, I believe
your test case is
Here is a document showing the results graphically.
https://filesender.renater.fr/?s=download=8ac3a214-edfa-4894-fa1f-27aba5a5522f
It really looks like the problem we had before (using bad kmesh).
We test it on two different compounds and in both cases WIEN2k_16 gives
a correct picture and
Dear All
Finally the problem is not completely solved.
More precisely, when we are doing GGA+SO calculations and using a
correct kmesh (no temporal symmetry), we obtain a symmetric
magnetocrystalline anisotropy, namely same MAE along [0 1 0] and [0 -1 0].
In contrast, when we are doing
Dear Lyudmila
The fact we have a small angle with axes is expected (also observed
experimentally). It is related to the monoclinic symmetry of the system
which permits it. However, you gave me an idea that I will test now and
comment soon ;)
Cheers
Xavier
Le 10/01/2018 à 10:40, Lyudmila a
Dear Xavier,
Just to be sure: do you have 80 k-points in the shifted/unshifted kmesh
= 5 4 4 ?
You have checked the convergence on the Rkmax (6,7), did you check it on
the number of k-points?
I see in the FM calculation also a slightly non-symmetric curve, isn't
it? Maybe the two
Dear Jaroslav
Thank you for your quick and detailled reply.
It seems to me that there is one important difference between my
calculations and yours.
Indeed, my calculations are done using P1 symmetry. In addition, the
unit cell for FM and AFM1 magnetic orders are exactly the same. I only
Dear Xavier,
your problem somewhat resembles me my problem I had when calculating
magnetic linear dochroism (MLD) on bcc Fe. The similarity is that we
both want to see small changes in electronic structure when rotating
magnetic field direction.
What help me:
1) run fine convergence
Dear Colleagues
I recently obtained a surprising result concerning the calculation of
the magnetocrystalline anisotropy energy (MAE) of SeCuO3.
This compound has a monoclinic symmetry (SG. P21/n) and is known to be
antiferromagnetically ordered at low temperature.
Here I provide the
Dear Pavel,
Thank you for your reply?
You are definitely right. In general cases, the expression of the total
energy should be modified. But in a uniaxial system, especially in cubic
case, the torque method is correct and we can get the MAE from the
expectation value of the derviative of the
Dear Bin Shao,
we did implement the torque method in WIEN2k some years ago, but after
gaining some experience we stopped using it. The problem is that the
conception is not quite correct: when s-o coupling is strong and
magnetization is in a general direction, spin is not along the
Dear all,
I intend to calculate magetocrystalline anisotropy (MCA) energy of the bcc
Fe monolayer. Since the MCA energy usually has an order of magnitude about
10^-6 eV, it's a tough work to get its calculated numerical value. The
reference PRB. *54*. 61 proposes a torque method and the MCA
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