Re: [Wien] question about tetra's choice of Emax

`Well, besides the :WAR nings, this is a good example for the problem.`
```
```
Apparently, at Gamma there is a huge "gap" and you find only 9 eigenvalues (bands) up to 2.1 Ry (while on other k-points there are up to 12 eigenvalues. Thus, even the output in scf2 is "wrong", the band-range maximum of band #10 is not 2.08 but will be "above" 2.1 (1.5+EF).
```
```
The TETRA method always integrates bandwise, ie. each band individually and I need an energy at EVERY k-point to do this integration. In lapw2 there is a crude fix for "missing eigenvalues" (it creates an arbitrarily large artificial eigenvalue), but in TETRA it is not done.
```
```
It might be save to calculate the "DOS" (and its integral) to some higher energy, but it is hard to estimate up to which value it is still save, since I would have to know the band dispersion. It could be that (in your case ?) only near Gamma a few k-points miss the 10th band, but in principle it could also be opposite. Since a reliable E-limit ("1.5-1.9 ?? in your case") is hard to estimate, I've chosen the "save" way.
```

Am 17.11.2016 um 00:55 schrieb pieper:
```
```OK, my mistake: I didn't check the scf for :WARN - which I should have
done, at least after running into the problem.

Just for the record a brief account what happened:

---------- Cofcc.struct --------
fcc-Co
F   LATTICE,NONEQUIV.ATOMS:  1
MODE OF CALC=RELA unit=ang
6.637022  6.637022  6.637022 90.000000 90.000000 90.000000
ATOM   1: X=0.00000000 Y=0.00000000 Z=0.00000000
MULT= 1          ISPLIT= 2
Co         NPT=  781  R0=0.00005000 RMT=    2.3300   Z: 27.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
0.0000000 1.0000000 0.0000000
0.0000000 0.0000000 1.0000000
48      NUMBER OF SYMMETRY OPERATIONS
.
.
.
(list of sym ops)
-------------------------------

Initialization via w2web, quick version, spin polarized marked, 10000 k
vectors entered (probably not significant), everything else left open
(defaults). Results without any complaints in

--------- Cofcc.in1 -----------
WFFIL  EF=.600081718450   (WFFIL, WFPRI, ENFIL, SUPWF)
7.00       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)
1    0.30      0.000 CONT 1
1   -4.57      0.001 STOP 1
2    0.30      0.005 CONT 1
0    0.30      0.000 CONT 1
K-VECTORS FROM UNIT:4   -9.0       1.5    35   emin / de (emax=Ef+de) /
nband
------------------------------

scf started in w2web without any changes in the menu. It converges in 11
cycles.

When I ploted the DOS from w2web I ran into the problem of Emax.lt.E_F

Looking into the scf's is a good idea:

--------- Cofcc.scf1up --------

ATOMIC SPHERE DEPENDENT PARAMETERS FOR ATOM  Co
:e__0001: OVERALL ENERGY PARAMETER IS    0.4003
OVERALL BASIS SET ON ATOM IS LAPW
:E1_0001: E( 1)=    0.4003
APW+lo
:E1_0001: E( 1)=   -3.7752   E(BOTTOM)=   -3.806   E(TOP)=   -3.744  1
2   175
LOCAL ORBITAL
:E2_0001: E( 2)=    0.3944   E(BOTTOM)=    0.168   E(TOP)=    0.621  0
1   124
APW+lo
:E0_0001: E( 0)=    0.4003
APW+lo

K=   0.00000   0.00000   0.00000            1
:RKM  : MATRIX SIZE    39LOs:  12  RKM= 6.24  WEIGHT= 1.00  PGR:
EIGENVALUES ARE:
:EIG00001:      -3.7586332   -3.7586332   -3.7586332   -0.0750175
0.3973462
:EIG00006:       0.3973462    0.3973462    0.4756761    0.4756761
********************************************************

:KPT   :      NUMBER OF K-POINTS:    286
----------------------------------------------------------

and

------------Cofcc.scf2up --------------------------------
:GAP  : -99999.   Ry = -9999.    eV  ( metallic )
Bandranges (emin - emax) and occupancy:
:BAN00001:   1   -3.782207   -3.758633  1.00000000
:BAN00002:   2   -3.774241   -3.758633  1.00000000
:BAN00003:   3   -3.767467   -3.758633  1.00000000
:BAN00004:   4   -0.075018    0.308043  1.00000000
:BAN00005:   5    0.252261    0.400466  1.00000000
:BAN00006:   6    0.341921    0.531620  1.00000000
:BAN00007:   7    0.397346    0.559086  1.00000000
:BAN00008:   8    0.439501    0.560197  1.00000000
:BAN00009:   9    0.472444    1.130465  0.32393899
:BAN00010:  10    1.052748    2.086705  0.00000000
:BAN00011:  11    1.362791    2.100100  0.00000000
:BAN00012:  12    1.460431    2.100017  0.00000000
Energy to separate low and high energystates:   -0.12502

:NOE  : NUMBER OF ELECTRONS          =  15.000

:FER  : F E R M I - ENERGY(TETRAH.M.)=   0.6000786246
:GMA  : POTENTIAL AND CHARGE CUT-OFF  12.00 Ry**.5

:POS001: ATOM    1 X,Y,Z = 0.00000 0.00000 0.00000  MULT= 1  ZZ= 27.000  Co

LMMAX  5
LM=   0 0  4 0  4 4  6 0  6 4

:CHA001: TOTAL VALENCE CHARGE INSIDE SPHERE   1 =   7.9401    (RMT=
2.3300 )
:PCS001: PARTIAL CHARGES SPHERE =  1 S,P,D,F,      D-EG,D-T2G
:QTL001: 0.2277 3.2151 4.4719 0.0180 0.0000 0.0000 0.0000 1.8125 2.6594
0.0000 0.0000 0.0000
Q-s-low E-s-low   Q-p-low E-p-low   Q-d-low E-d-low   Q-f-low
E-f-low
:EPL001:  0.0001 -3.7727    2.9953 -3.7686    0.0004 -3.7693    0.0002
-3.7677
Q-s-hi  E-s-hi    Q-p-hi  E-p-hi    Q-d-hi  E-d-hi    Q-f-hi
E-f-hi
:EPH001:  0.2275  0.1987    0.2198  0.3397    4.4715  0.4145    0.0179
0.4072

:CHA  : TOTAL VALENCE CHARGE INSIDE UNIT CELL =       8.323939

:SUM  : SUM OF EIGENVALUES =          -9.209154185

QTL-B VALUE .EQ.   22.75945 in Band of energy   1.99144  ATOM=    1
L=  2
Check for ghostbands or EIGENVALUES BELOW XX messages
switch), check RMTs  !!!

NBAND in QTL-file:           9
----------------------------------------------------------------------------

So yes, there are unoccupied bands above no.9, but there is a qtl
problem with single atom of the structure ...

grep for :WAR in the scf yields the warnings one clearly should not ignore:

:WARN : You should change the E-parameter for this atom and L-value in
case.in1 (or try the -in1new
:WARN : QTL-B value eq.   3.98 in Band of energy   0.64376  ATOM=    1
L=  2
:WARN : QTL-B value eq.   2.97 in Band of energy   0.29294  ATOM=    1
L=  2

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

Am 16.11.2016 16:06, schrieb Peter Blaha:
```
```The question is: what does your scf2up/dn files (and the scf1up/dn
files say ?

In case.in1 there should be an EMAX of 1.5 ?

and in scf1up/dn there should be eigenvalues up to 1.5+EF ??

and in scf2up/dn there is a list of "bandranges". Are there "empty"
band ranges (band which have zero occupation) ??

Of course it could simply be that you have so steep bands that one
does not catch an empty band within 1.5+EF Ry. In this case one has to
increase EMAX in case.in1. And yes, if this really happens, one should
give a :WAR ...(and I don't think this is there yet ..., but I would
need a case where this happens).

Regards

On 11/16/2016 12:25 PM, pieper wrote:
```
```Thanks for the quick response!

Sorry, I did not fully catch the problem of consistency between what is
calculated in lapw1 and integrated in tetra.

However, your PS and PPS leave me worried about where things go sideways
with something as simple as fcc Co should be.

As for the version, my VERSION file says
WIEN2k_14.2 (Release 15/10/2014)
which to my knowledge is not too bad? It does not include the dynamical
Emax in lapw1?

With that version, kgen 10000 vectors, spin-resolved, and everything
else default in w2web, I get from tetra something like the file below.
Emax is apparently changed to a value below E_F.

I understand that this might lead to problems already in the scf because
the wrong states are occupied, but in that case again I cannot rely on
the DOS, even when I increase Emax in .in1 and run lapw1 ... I have to
re-run the scf, correct?

-----  Co-fcc.outputtup ------
Co-fcc             #

IAV                         :  0
NPRINT                      :  1
2 CASES FOR DOS            :  ATOM   L

cc-Co
LATTICE CONST.= 6.79300 6.79300 6.79300   FERMI ENERGY=   0.56702
48 <; NMAT <;   63   SPIN=2   NATO=   2
JATOM  1  MULT= 1  ISPLIT= 2  tot,0,1,2,D-eg,D-t2g,3
CASE 1 :   ATOM NUMBER  0   COLUMN READ  0   DOSTYPE=total-DOS
CASE 2 :   ATOM NUMBER  1   COLUMN READ  1   DOSTYPE=  1:total
We will add            0  DOS-cases together:
BAND LIMITS OF BAND   1 ARE  -3.81359  -3.79544
BAND LIMITS OF BAND   2 ARE  -3.80710  -3.79544
BAND LIMITS OF BAND   3 ARE  -3.80235  -3.79544
BAND LIMITS OF BAND   4 ARE  -0.07833   0.28402
BAND LIMITS OF BAND   5 ARE   0.24033   0.37076
BAND LIMITS OF BAND   6 ARE   0.32045   0.48759
BAND LIMITS OF BAND   7 ARE   0.37076   0.51438
BAND LIMITS OF BAND   8 ARE   0.40511   0.51502
BAND LIMITS OF BAND   9 ARE   0.43442   1.04422
EMAX reduced due to lower HIGHEST BAND-minimum
EMIN, DE, EMAX              :  -0.50000   0.00200   0.43442

EMIN=  -0.50000 EMAX=   0.43442 EFACTR=    499.99996948 ESTEP =
0.00200
ENERGY BAND    1 THROUGH    9 ENERGY CHANNEL:    1   TO  468
NUMBER OF K-POINTS:         165
NUMBER OF TETRAHEDRONS:         693
#  BAND    9
#EF=   0.56702     NDOS= 2     NENRG=  468    Gaussian bradening:
0.00300
NUMBER OF ELECTRONS UP TO EF         :    0.0000

DOS in states/Ry/spin
smearing           1  0.398942274850643        2.00000000000000
smearing           1  0.398942274850643        2.00000000000000
# ENERGY    0 total-DOS        1   1:total
-0.50000     0.00   0.0000     0.00   0.0000
-0.49800     0.00   0.0000     0.00   0.0000
-0.49600     0.00   0.0000     0.00   0.0000
.
.
.
------------------------------------------------------------------

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

Am 16.11.2016 07:41, schrieb Peter Blaha:
```
```The DOS is calculated up to a value for which we can guarantee that
the DOS is correct and complete.

Of course, the DOS up to the highest band-maximum would be non-zero,
but there is a chance that some (maybe a lot) of DOS is missing and a
user would not notice this and "misintewrprete" this wrong DOS.

Now he can trust that the calculated DOS is ok, and if he needs higher
DOS, he has to increase the emax in case.in1 and/or in case.int.

PS: You are probably using an older WIEN2k version, because now we use
a "dynamical" Emax in case.in1, which takes the actual EF into
account. But of course in cases of very steep bands above EF, the
default in1 file may still be insufficient.

PPS: In your situation it could even be, that the scf calculation is
"wrong", since you occupied the wrong bands ....

Am 15.11.2016 um 19:12 schrieb pieper:
```
```Hello, mailing list,

yesterday I had for the first time some dispute with the way tetra
automatically chooses its input energy range. I would like to
understand
why the particular automatic choice of Emax was introduced.

Until then it worked so well that I didn't even notice that Emax is
automatically adjusted, but then I wanted to illustrate Wien2k by
calculating the example fcc Ni. I took Co instead of Ni, lattice
constant adjusted to 6.637, RMT to touching spheres. I used w2web for
initialiazation and initiating scf, kgen with 10000 vectors,
spin-polarized in an FM starting configuration, no spin-orbit
coupling.

Then I chose DOS from the Tasks menu, skipped the optional steps lapw1
and qtl, used lapw2 -qtl, configured .int to calculate just the total
DOS (the default). When I proudly presented the result of dosplot to a
visitor the plot ended below the Fermi energy ...

Increasing Emax in .int did nothing, as the experts probably could
have
told me beforehand. The (in this case in my view annoying) automatic
choice of Emax that kicks in is indicated in the header of .outputtup
(as well as in the user guide - and yes, I know one should read it):

.
.
.
BAND LIMITS OF BAND   8 ARE   0.40511   0.51502
BAND LIMITS OF BAND   9 ARE   0.43442   1.04422
EMAX reduced due to lower HIGHEST BAND-minimum
EMIN, DE, EMAX              :  -0.50000   0.00200   0.43442

The problem in this case is that the 'lower highest Band-minimum' is
BELOW the Fermi-energy:

******** EF and DOS at fermi level *******
0.56702     0.00              0.00

So one MUST go back to the (in principle optional) lapw1 step with
some
larger Emax in .in1 (as indicated in the DOS menu and in the UG).
Increasing Emax there appears to me a little clumsy since one has to
guess an Emax that will generate a band with a band minimum above E_F.

Why not have tetra choose Emax as the minimum of the Emax input in
.int
and the highest Band-MAXIMUM?

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

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