[Wien] Q: charge lost in SO calculation depending on LAPW / APW+lo

Wed Nov 16 09:01:50 CET 2005

I second this. I had not seen the energy limits (sorry, Peter)... the 
problem is in your input cutoff parameters, not with the spin-orbit 
interaction as such.

Peter Blaha wrote:
> Please check the scf file, if the Fermi integration works ?
> Do you get the proper valence charge
> grep ':CHA  ' case.scf
> or is this value already smaller ?
> 
> Such small unit cells require many k-points (100-10000) !!!! Results with
> Gamma only are nonsense.
> 
> For the second variational procedure you MUST use a larger E-window in
> case.in1. Thus increase the default 1.5 and do NOT decrease it to 0.9
> 
> I do NOT understand the statement, that LAPW for p is "unstable" ? 
> 
> To be sure I understand you correctly: You loose charge ONLY for a
> 6s=LAPW, 6p=APW+lo,  6p-RLO calculation ? All other combinations are fine ?
> 
> After all, why do you change the default in1 file and play with APW/LAPW ?
> If one plays around, than for best convergence use APW+lo for d, but LAPW for
> s+p
> 
> Regards  
> 
> 
>>Dear all,
>>
>>For bismuth (Bi) I found the following behavior, which I do not understand:
>>
>>When 6s states were described by LAPW's and 6p states by APW+lo's
>>and when the spin-orbit (SO) interaction was included using a relativistic 
>>local p1/2 orbital, 0.33 electrons were lost as can be seen from the 
>>following output of MIXER:
>>
>>:NEC01: NUCLEAR AND ELECTRONIC CHARGE   83.00000  82.67338   1.00395
>>
>>This charge disappears from the p channel as can be seen when QTL is compared 
>>for the above case and a case where the 6s states are also described by 
>>APW+lo's:
>>
>>:QTL001: 1.2922 1.3993 9.8302 0.0642 ....  (above case)
>>:QTL001: 1.2631 1.7246 9.8203 0.0643 .... (when 6s is described by APW+lo's)
>>
>>No charge was lost when 6s was described by APW+lo's, when 6s and 6p were both 
>>described by LAPW 's (but this calculation is unstable, so I did just one 
>>iteration), or when no p1/2 orbital was included. 
>>
>>I checked that there are no linear dependencies in the second-variational 
>>secular equation (the overlap matrix is positive definite) and that this 
>>behavior does not depend on Emax or the choice of basis for the d states, 
>>i.e., APW+lo or LAPW. There were no QTL-B warnings or other warnings that I 
>>am aware of.
>>
>>When no p1/2 orbital orbital was included, the total energy was insensitive to 
>>whether LAPW or APW+lo was used for 6s and 6p, so in principle these choices 
>>form an equally good basis for LAPW1
>>
>>I found this behavior for both the A7 structure (with 2 atoms per unit cell) 
>>and for simple cubic Bi [space group Pm-3m (number 221), a = 6.18 Bohr,
>>Gamma point only with temperature smearing, Eval=0.001 Ry]. The above data are 
>>for the latter calculation, which is simpler. For this calculation my files 
>>case.in1 and case.inso are:
>>
>>********* case.in1 *************
>>WFFIL        (WFPRI, SUPWF)
>>  7.00       10    4 (R-MT*K-MAX; MAX L IN WF, V-NMT
>> .07680   4   0      global e-param with N other choices, napw
>> 0   -0.364     0.010 CONT 0
>> 1    0.205     0.000 CONT 1
>> 2   -1.273     0.010 CONT 0
>> 2    0.113     0.000 CONT 0
>>K-VECTORS FROM UNIT:4   -4.0       0.9      emin/emax window
>>********** end of case.in1 ************
>>
>>********* case.inso ***********
>>WFFIL
>> 4  4  0                      llmax,ipr,kpot
>> -10.0000   0.90000           emin,emax (output energy window)
>>   0.  0.  1.                 direction of magnetization (lattice vectors)
>>  1                           number of atoms for which RLO is added
>> 1  0.205  0.000  CONT
>> 0 0 0 0 0             number of atoms for which SO is switch off;atoms
>>********** end of case.inso ************
>>
>>Finally, I checked that this same behavior occured both with the precompiled 
>>WIEN2k package and when I compiled WIEN2k with the Portland Group compiler 
>>pgf90, with and without optimization.
>>
>>My question is, whether anyone has had similar problems? Whether somebody 
>>could comment on its cause? I would really like to know, whether there is a 
>>bug in the program or whether there is some criterium according to which I 
>>can choose my basis set in one way but not in another way and of which I am 
>>not aware.
>>
>>I hope that this question is not too hard. 
>>Any help would of course be greatly appreciated! 
>>
>>
>>Sincerely,
>>
>>Eeuwe Sieds Zijlstra
>>Theoretical Physics
>>University Kassel
>>Germany
>>_______________________________________________
>>Wien mailing list
>>Wien at zeus.theochem.tuwien.ac.at
>>http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>>
> 
> 
> 
>                                       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/
> --------------------------------------------------------------------------
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> 

-- 
Dr. Torsten Andersen        TA-web: http://deep.at/myspace/
AG Hübner, Department of Physics, Kaiserslautern University
http://cmt.physik.uni-kl.de    http://www.physik.uni-kl.de/