[Wien] QTL-B and "Eigenvalues Below..."

[Stefaan Cottenier]

Dear wien2k community,

I ran into a case that gave a QTL-B error in the first iteration. 
Following the FAQ, I therefore set the default 0.30 linearization energy 
to about 0.2 Ry below the :FER that is found in case.scf2, and adjust 
the linearization energies of the deeper states to the eigenvalues found 
in case.scf1. I have then the following case.in1c (the first atom is Cu, 
the second is Ge):

WFFIL        (WFPRI, SUPWF)
 6.15       10    4 (R-MT*K-MAX; MAX L IN WF, V-NMT
  0.10    5  0      (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global 
APW/LAPW)
 0    0.10      0.000 CONT 1
 0   -8.12      0.002 STOP 1
 1    0.10      0.000 CONT 1
 1   -4.99      0.005 STOP 1
 2    0.10      0.010 CONT 1
  0.10    5  0      (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global 
APW/LAPW)
 1    0.10      0.000 CONT 1
 1   -7.76      0.002 STOP 1
 2   -1.42      0.005 CONT 1
 2    0.10      0.000 CONT 1
 0    0.10      0.000 CONT 1
(snip)

Nevertheless, the same QTL-B error reappears (last lines from case.output2):

   QTL-B VALUE .EQ. **********   in Band of energy   -8.93817   ATOM=    
2   L=  2

I'm a bit puzzled by this, as atom nr. 2 (Ge) should have no states near 
that energy, certainly no d-states.The linearization energies used for 
this second trial are nicely consistent with the content of the new 
case.scf2 and case.scf1:

grep :FER case.scf2 ==> :FER  : F E R M I - ENERGY(TETRAH.M.)=   0.33183

case.scf1:

:EIG00001:      -8.1239527   -7.7633883   -7.7633873   -7.7633873   
-7.7633588
(snip)
:EIG00186:      -7.7595614   -7.7595564   -7.7595506   -7.7595506   
-7.7595488
:EIG00191:      -4.9882067   -4.9882067   -4.9882066   -1.4337422   
-1.4337422
:EIG00196:      -1.4335714   -1.4333581   -1.4332873   -1.4332873   
-1.4332455

A second inspection shows there is a message "8 EIGENVALUES BELOW THE 
ENERGY  -12.00000" in case.output1 (actually in case.output2_3 of a 
k-point parallel run, which corresponds to the case.output2_3 where I 
got the QTL-B message). That message is there with and without adjusting 
the linearization energies. There should not be any eigenvalues so deep, 
and changing Emin in case.in1c to a very low value of -20.0 leads to the 
same message (now 8 eigenvalues below -20.000). This message is probably 
the source of the error, rather than the linearization energies. But I 
do not understand where it comes from...?

Another observation is that in case.scf2_3 there are many '****' 
strings, for all atoms:

:POS002: AT.NR.  -2 POSITION = 0.37456 0.12507 0.12507  MULTIPLICITY = 12

       LMMAX 28
       LM=   0 0  1 1 -1 1  2 0  2 2 -2 2  3 1 -3 1  3 3 -3 3  4 0  4 2 
-4 2  4 4 -4 4  5 1 -5 1
         5 3 -5 3  5 5 -5 5  6 0  6 2 -6 2  6 4 -6 4  6 6 -6 6

:CHA002: TOTAL CHARGE INSIDE SPHERE   2 = ************
:PCS002: PARTIAL CHARGES SPHERE =  2 
S,P,D,F,PX,PY,PZ,D-Z2,D-X2Y2,D-XY,D-XZ,D-YZ
:QTL002:************************************************************************************
        Q-s-low E-s-low   Q-p-low E-p-low   Q-d-low E-d-low   Q-f-low 
E-f-low
:EPL002:******** -8.8617  ******** -8.8746  ******** -8.8802  ******** 
-8.8790
        Q-s-hi  E-s-hi    Q-p-hi  E-p-hi    Q-d-hi  E-d-hi    Q-f-hi  E-f-hi
:EPH002:  0.3394 -0.2555    0.3053  0.1277    0.0300 -0.4098    0.0014 
-0.0723

                      QXX         QXY         QYY         QZZ       UP TO R

:VZZ002:        ************************************************       2.050

It may be useful to mention the sphere radii, as they are rather small 
for Ge (due to atoms that lie close to each other):

RMT = 2.31 for Cu, which leads to this in case.outputst:

 TOTAL CORE-CHARGE:                   10.000000
 TOTAL CORE-CHARGE INSIDE SPHERE:     10.000000

RMT = 2.05 for Ge, which leads to this in case.outputst:

 TOTAL CORE-CHARGE:                   12.000000
 TOTAL CORE-CHARGE INSIDE SPHERE:     11.999832

Both seem OK for me.

I have ran many similar cases without problems, only this particular 
structure (and a few variants of it) lead to trouble. I'm out of ideas. 
Does anybody have a hint?

Thanks,
Stefaan



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