[Wien] Questions about the input file of LAPW1 (case.in1c)

[YOOSOO YI]

Dear all,



Recently, I had sent a mail about a failure of calculations in the first
step of SCF cycle. I had solved the problem by changing a procedure for
preparing case.struct file according to User Guide, FAQ page, and reply of
my previous questions. Now, I have another question about the use of
case.in1c file which is the input file of LAPW1.



Following is the part of the case.in1c file that I used for my calculation.





Now, I have another question about the use of case.in1c file which is the
input file of LAPW1, because another ERROR was occurred on the LAPW2 in the
second step of SCF cycle with





*## Original case.in1c file generated from WIEN2k*

WFFIL  EF= 0.50000       (WFFIL, WFPRI, ENFIL, SUPWF)

6.0      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   -5.57      0.001 STOP 1

 1    0.30      0.000 CONT 1

 1   -3.12      0.001 STOP 1.

K-VECTORS FROM UNIT:4  -14.0       1.5  2565   emin / de (emax=Ef+de) /
nband



Since the SCF calculation was failed in the second step of SCF cycle with
the ERROR message of LAPW2 related to the GHOST BAND, I was tried to fix
the problem by modifying case.in1c file according to the relevant
references. In FAQ page in WIEN2k official site (
http://www.wien2k.at/reg_user/faq/qtlb.html), there is a tip for modifying
case.in1c file with the calculated “:FER” value in case.scf2 file, and
following is referred from that page.



*From the scf2 file above you see that the Fermi energy (and also the state
where the large QTL-B value occurs) is above 1 Ryd. The default
energy-parameters in case.in1 are at 0.3 Ry, and this is too far from the
actual eigenvalues, so that the "linearization" is not accurate enough
anymore. You may need to set the energy parameters in case.in1 and replace
all 0.3 by 0.8 (in general, take a value about 0.2 Ry below EFermi). *



Similar to the example in the FAQ page, I had tried to change the
parameters in case.in1c file with the calculated “:FER” value in case.in2c
file. Following is the part of case.in1c file that modified from the
automatically generated by LSTART. The calculated “:FER” value was ~0.1 Ry.
So, I had changed “EF=###” value in LINE 1 from “EF=0.50000” to
“EF=0.10000”. And then I also had changed the GLOBAL E-PARAMETER (defined
Etrial in User Guide) and some of energy parameters for each l-resolved
local orbitals (defined El in User guide). The Etrial in LINE 1 and El
values in LINE 4 and LINE 6 were changed from 0.30 to -0.10 as EF-0.2 as
mentioned in the FAQ page.



*## Modified case.in1c file after the calculation is failed in the second
step of SCF cycle*

WFFIL  EF= 0.10000       (WFFIL, WFPRI, ENFIL, SUPWF)

6.0      10    4 (R-MT*K-MAX; MAX L IN WF, V-NMT

-0.10    4  0      (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
APW/LAPW)

 0    -0.10      0.000 CONT 1

 0   -5.57      0.001 STOP 1

 1    -0.10      0.000 CONT 1

 1   -3.12      0.001 STOP 1.

K-VECTORS FROM UNIT:4  -14.0       1.5  2565   emin / de (emax=Ef+de) /
nband



In the User Guide of WIEN2k, it is said that the “EF=####” option flag in
LINE 1 will replace the Etrial value in LINE 3. And El values with
“de=0.000” at LINE 4 and LINE 6 will be replaced by the Etrial value in
LINE 3 as described in the User Guide. And it means that the “EF=####”
option flag in LINE 1 will define the trial energy parameters, i.e., Etrial
and El with de=0.000, in case.in1c file.



Now this is the question. In this case, are there any other necessities to
change those Etrial and El values in LINE3, LINE 4 and 6? Why should I
change those values as described in the FAQ page? Does not “EF=####” option
flag define other energy parameters as mentioned in the User Guide? If so,
the only thing that I have to do to modify the case.in1c file with the
calculated “:FER” value in case.scf2 file is changing “EF=####” value in
LINE1. Is it correct?



Thanks for reading such long questions. Any help will be gratefully
appreciated.


Best regards, YOOSOO
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