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
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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