[Wien] strange(?) LOPW - Error

Fecher, Gerhard fecher at uni-mainz.de
Sun Jan 28 12:20:06 CET 2024


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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