1. CHARGE CONVERGENCE: I know this has been discussed before, but it
seems it didn't change in Wien2k_18. Here is a typical example of the
charge convergence history of the last few iterations of FM+SOC
(ferromagnetic + spin orbit coupling) calculation:
:ENERGY convergence: 0 0.0001 .0001320450000000
:CHARGE convergence: 0 0.001 .0027578
:ENERGY convergence: 1 0.0001 .0000497650000000
:CHARGE convergence: 0 0.001 .0050904
:ENERGY convergence: 1 0.0001 .0000557650000000
:CHARGE convergence: 0 0.001 .0004672
:ENERGY convergence: 1 0.0001 .0000220050000000
:CHARGE convergence: 1 0.001 -.0001786
Something strange happens with charge convergence, is this OK?
This is ok.
2. LIMITS in inso and in1c files: in order to avoid large vector files I
am changing the energy limits in inso and in1c files for band structure
calculations. SCF is done with default inso and in1c files, then I do
save_lapw, then I edit case.inso and case.in1c files, and then I do
FM+SOC band structure calculation:
#! /bin/bash
x lapw1 -band -up -p
x lapw1 -band -dn -p
x lapwso -up -p
I am using emin/emax -0.5 0.5 in both files (inso and in1c) without
changing anything else, then I have bands from limited energy range. I
just want to make sure that this procedure is fine.
No, this is NOT ok. You must not change Emax in case.in1c !
If you do, your basis set for the spin-orbit step is limited and
eigenvalues will change as compared to the scf calculation.
You can reduce emax in case.inso if you are not interested in the bands
at higher energies.
3. FM+SOC convergence: I am doing FM+SOC calculations for different
in-plane magnetization M directions in a 2D Fe(001) ferromagnetic layer.
Actually an older Wien2k_14 version was not working well for this,
results for generic M directions were really strange. Wien2k_18 seems
much better, however, when starting things from the scratch (each M
angle completely separate calculation) it seems that for some M angles
the result is off, as if it didn't actually properly converge. I am
using a fairly dense mesh for SCF (2000k, 25 25 3), and -ec 0.0001 -cc
0.001. Should I maybe try -fermit setting in init_lapw, and what would
be a reasonable value? Do I always need to use instgen_lapw before
init_lapw when starting a new case? Should I perhaps do each next M
angle on top of a previously converged M angle (and save_lapw for each M
angle)?
Doing separate calculations for different directions may / may not yield
correct results.
The proper (save) way is to use ONE case.struct file for all cases.
i) select all directions of magnetization first.
ii) Produce (using init_so) struct files, which are the same for all
cases (do not change after init_so) and use this struct file for ALL
(also non-so) calculations.
This works as:
a) generate normal struct file.
b) init -b -sp ....
c) init_so with first direction, accept the generated structure
d) init_so with second direction, accept ...
repeat this for all desired directions (or until you have a P1 structure
(only identity).
e) with this setup (no new init_lapw !!!!) execute:
runsp -ec ... and save as "non-so"
runsp -so ... and save as "so-dir_2"
restore non-so; edit case.inso and put the first direction in;
runsp -so ... and save as "so-dir_1"
In this way, you can also compare the force-theorem (:SUM of first
iteration (2 numbers !) with the scf solution.
Best,
Lukasz
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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: bl...@theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at
WWW: http://www.imc.tuwien.ac.at/TC_Blaha
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