[Wien] strange(?) LOPW - Error

[Peter Blaha]

Dear Gerhard,

This is (at least for me) a well known behavior.

We attach to each local orbital a fictitious plane wave with a k-vector 
K. In addition we require that LOs are orthogonal to each other and this 
requirement becomes a problem if you have many equivalent atoms (8 Ga in 
your case) and high l=2 (makes 5 d-LOs per atom) and a small RKmax, 
because then we run out of K vectors.
Maybe we are doing the orthogonality check too stupid and could reduce 
the requirements when running over equivalent atoms, but I've never 
tested this in details.

In your case, a quick test seems to run through when RKmax = 7.5 or bigger.
Alternatively, you may want to split the 8 Ga in 4+4 , but in such a way 
that more symmetry survives and not just in P1.

Peter

Am 28.01.2024 um 12:20 schrieb Fecher, Gerhard:
> Hallo Peter,
> I observed some unexpected (maybe strange) behaviour of lapw1 (Wien2k Version 23.2 compiled with OneAPI 23.1)
> I wanted to test if there is a ferro- or antiferromagnetic coupling in MnGa4
> 
> 1) I started with the regular structure (just spin polarized) I m-3m  1 Mn atom 4 Ga atoms (MnGa4_aexp.struct)
> this one was running without problems (a small (ferro) magnetic moment of 0.6 seems to exist, I did not check energy and higher precesions),
> 
> 2) then I made the antiferromagnetic structure P m-3m  with 2 Mn atoms and 8 Ga atoms  (MnGa4_afm-failes.struct) and named the Mn by 1 and two
> here the  LOPW - Error (at the Ga atom, see below),
> 
> 3) I splitted the Ga atoms in two groups P 4mm with 2 Mn and 2x4 Ga atoms (MnGa4_afm-2.struct) and named both Mn and Ga toms to distinguish same.
> this one was running without problems, too (an antiferromagnetic mpoment of +-1.2 muB seems to exist).
> (indeed, this splitting doesn't make much sense, from symmetry point of view)
> 
> In all three cases the structure in reduced P1 symmetry has the same lattice parameters and positions (2 Mn and 8 Ga)
> all calculations were simply initialized with precision 1, the parameters in case.in1 are principally always the same, changing the precesion or other parameters in case 2) did not help.
> The error appeared independet on the magnetic setting in case.inst (ferro, antiferro, with and without magnetic moment at Ga).
> (the same LOPW error appears when I replace Ga Z=31 by Ge Z=32 (not with Al or Au))
> 
> I wonder why this LOPW error appears in the P m-3m structure but not in the others.
> 
> (as the P 4mm structure has only 8 symmetry operations it would be faster to run the P m-3m structure (48 symmetry operations))
> 
> some detail of the error (note: running lapw1 -dn by hand has the same result as lapw1 -up):
> the message at the end of case.scf1up (or output1up) is
> :INFO  : LOPW-exhausted for atom    3 PASS 1  had to reduce check 0.010000
> :INFO  : LOPW-exhausted for atom    3 PASS 2  had to reduce check 0.005000
> :INFO  : LOPW-exhausted for atom    3 PASS 3  had to reduce check 0.002500
> :INFO  : LOPW-exhausted for atom    3 PASS 4  had to reduce check 0.001250
> :INFO  : LOPW-exhausted for atom    3 PASS 5  had to reduce check 0.000625
> 
> Ciao
>   I don't expect an answer today, better have a nice weekend,
> Gerhard
> 
> 
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:  http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html

-- 
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300
Email: peter.blaha at tuwien.ac.at    WIEN2k: http://www.wien2k.at
WWW:   http://www.imc.tuwien.ac.at
-------------------------------------------------------------------------