[Wien] Lapw1 error
EB Lombardi
lombaeb at science.unisa.ac.za
Thu May 12 08:43:35 CEST 2005
Dear Prof Blaha
In all cases, I use a separation energy of -10 Ry in lstart to place the
P-2p in the valence as LO's (to prevent charge leakage, as you
mentioned). Using this approach the charge leakage is:
For P:
TOTAL CORE-CHARGE: 4.000000
TOTAL CORE-CHARGE INSIDE SPHERE: 3.995122
TOTAL CORE-CHARGE OUTSIDE SPHERE: 0.004878
For C atoms:
TOTAL CORE-CHARGE: 2.000000
TOTAL CORE-CHARGE INSIDE SPHERE: 1.999732
TOTAL CORE-CHARGE OUTSIDE SPHERE: 0.000268
The leakage for P is still an order of magnitude larger than for C.
The .in1c file contains (default input) for P:
0.30 4 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
APW/LAPW)
1 0.30 0.000 CONT 1
1 -8.80 0.005 STOP 1
0 -0.79 0.010 CONT 1
0 0.30 0.000 CONT 1
For the sake of completeness I am attaching the struct files, etc. which
I attached to the original e-mail.
Note: for the 'plain' LAPW calculation mentioned in my previous e-mail
(3.1), the fermi level lies at 1.30409 Ry. So according to the FAQ, I
also tried replacing all '0.30' entries in .in1c with '1.00'. This does
not solve the problem either, but results in ghost bands at -2.2662 and
-2.2663 Ry.
Best regards
Enrico
--
Dr E B Lombardi
Physics Department
University of South Africa
P.O. Box 392
0003 UNISA
South Africa
Tel: +27 (0)12 429-8027
Fax: +27 (0)12 429-3643
e-mail: lombaeb at science.unisa.ac.za
Peter Blaha wrote:
>Just a guess:
>
>Have you checked for any core leakage of the P site ?
>Check case.outputst for corresponding WARNINGS.
>With such small spheres it might be that you need to decrease the -6.0 Ry
>core-valence seperation energy and include P-2p (maybe even 2s) states in
>the bandstructure.
>Otherwise the valence states are not strickly orthogonal to the core and
>this leads to ghostbands.
>
>
>
>>Dear Lyudmila and Wien authors.
>>
>>Regarding the previous 'ghost band' errors I mentioned in the previous e-mails
>>on this topic:
>>
>>1. There has been an additional error in the APW calculation (using
>>unmodified .in1c) which I did not notice originally. In the scf files the
>>following suspicious lines occur:
>>QTL-B VALUE .EQ. ********** in Band of energy 0.00000
>>QTL-B VALUE .EQ. ********** in Band of energy 0.00000
>>Similarly for a mixed APW/LAPW run (see below):
>>QTL-B VALUE .EQ. 2.35833 in Band of energy 0.00000
>>QTL-B VALUE .EQ. 2.35913 in Band of energy 0.00000
>>
>>The problem is that there is no band of energy 0.00000.
>>
>>
>>2. I tried your suggestion of using a value of -0.2 Ry for the P_s LO (using
>>APW). This results in a similar crash, with a ghost band at -1.307337 Ry.
>>(the original unmodified APW run had a ghost band at -3.34806 eV)
>>
>>3. I also tried several other combinations, none of which worked, as
>>follows:
>>
>>3.1: When using LAPW rather than APW for all atoms (default .in1c), the SCF
>>cycles converge for the initial geometry structure only. However, when using
>>"min -p -sp -s 1" for a geometry optimization, lapw2 crashes again in the
>>first SCF cycle of the new geometry, with many ghost bands at -0.39479,
>>-0.38044, +0.26593, +0.28952, +0.33388, +0.37419, +0.41470, .......... Ry
>>
>>3.2: When mixing LAPW for the P-s orbitals and APW for everything else, the
>>results are similar to 3.1 with the SCF cycles converging for the initial
>>geometry, but crashing in the first SCF cycle of the second geometry
>>optimization step with ghost bands at +0.20051, +0.52656, +0.79082, +1.25045
>>Ry.
>>
>>3.3 Changing sphere sizes: When using plain LAPW with default input, but
>>changing the sphere sizes (Rmt_C from 1.30au to 1.37au, Rmt_P from 1.42au to
>>1.40au), this results in a crash in the 5th SCF cycle of the initial geometry
>>with a message of "FORTRAN STOP L2main - QTL-B Error".
>>This is an "improvement" since that lapw2 is able to stop with an error
>>message, rather than just crashing on the ******* in the *.help_ files. The
>>QTL errors are not so large either. This case is rather perplexing since the
>>sphere size of P was reduced, while the sphere sizes of the C atoms were
>>increased.
>>
>>For the 5th SCF cycle, the scf files contained:
>>phos.scf2dn: QTL-B VALUE .EQ. 6.99287 in Band of energy 0.15828
>>phos.scf2dn_1: QTL-B VALUE .EQ. 4.61602 in Band of energy 0.07087
>>phos.scf2dn_2: QTL-B VALUE .EQ. 4.55460 in Band of energy 0.63894
>>phos.scf2dn_3: QTL-B VALUE .EQ. 3.96843 in Band of energy 0.30243
>>phos.scf2dn_4: QTL-B VALUE .EQ. 6.99287 in Band of energy 0.15828
>>phos.scf2p: QTL-B VALUE .EQ. 6.99287 in Band of energy 0.15828
>>phos.scf2up_1: QTL-B VALUE .EQ. 5.72604 in Band of energy 0.05845
>>phos.scf2up_2: QTL-B VALUE .EQ. 5.74549 in Band of energy 0.62481
>>phos.scf2up_3: QTL-B VALUE .EQ. 4.91945 in Band of energy 0.28777
>>phos.scf2up_4: QTL-B VALUE .EQ. 7.45940 in Band of energy 0.14799
>>
>>Note: calculations of other impurities with the same small C spheres had no
>>problems.
>>
>>Any suggestions would be welcome
>>
>>Best regards
>>
>>Enrico
>>
>>
>>Lyudmila Dobysheva wrote:
>>
>>
>>
>>>Dear Enrico,
>>>
>>>So, the APW+lo makes the first density not good, as there appeared the level
>>>with -3.34 Ry. I have looked in my old calculations (pure phosphorus and
>>>alloys with phosphorus) and found that I was completely wrong: these
>>>phosphorus s-electrons should be in the valence band. I mixed them with P2s.
>>>The APW+lo calculation in the first iteration is wrong, the -0.79 which
>>>comes from the atomic density estimate is more correct. Now I think that it
>>>is just opposite to my first guess - too low, in my calculations the valence
>>>band starts at -0.2 Ry and these P s-electrons should lie there. The wrong
>>>linearization energy (too low!) gave a ghost at -3.34 Ry. The LAPW scheme
>>>has apparently a wider interval of energy where linearization works well,
>>>and does not give the ghost, and the APW+lo fails. So, I think that now, if
>>>you can calculate with the LAPW scheme, you can obtain a convergent
>>>calculation in it, and then try to continue with APW+lo. And as a test it
>>>would be very interesting to make a calculation APW+lo at -0.2 Ry or near,
>>>and look at the result, please write me the result - my settings of the
>>>system do not allow me to repeat calculation of your system quickly.
>>>By the way, I was using then:
>>> 0.30 3 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
>>>APW/LAPW)
>>>0 -0.79 0.010 CONT 0
>>>0 0.30 0.000 CONT 0
>>>1 0.30 0.000 CONT 1
>>>
>>>This is a good observation, I'll remember that sometimes APW+lo and LAPW may
>>>give such different results at the first stages.
>>>
>>>Best regards
>>> Lyudmila Dobysheva
>>>------------------------------------------------------------------
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>>>426001 Izhevsk, ul.Kirova 132 | Fax: 7 (3412) 250614
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>>>
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>>>
>>>
>>>
>>>
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>>
>>
>>
>
>
> P.Blaha
>--------------------------------------------------------------------------
>Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
>Phone: +43-1-58801-15671 FAX: +43-1-58801-15698
>Email: blaha at theochem.tuwien.ac.at WWW: http://info.tuwien.ac.at/theochem/
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