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[Vincenzo Fiorentini <vincenzo.fiorentini@dsf.unica.it>]

Hi, I don't know if this has got to do with your error message, but  
note that LDA/GGA fail for YMnO (it is artificially metallic, as the  
cuprates, e.g. CuO, YBCO6, CaYCuO, etc.). You need SIC (better) or GGA 
+U (may be) for that. See B. Van Aken, T. M. Paalstra, A. Filippetti,  
and N. Spaldin, Nature Mater. 3, 164 (2004)

best - VF

On 12 Dec 2008, at 6:56 AM, Skorlans Mathew wrote:

> Dear Users,
>
>   I am trying to optimize the lattice constant for cubic YMnO3 in  
> Para, Ferro
> and Antiferro phases. I could get nice optimization of acell for  
> Para and Ferro
> phases. But, When I tried to optimize the Antiferro phase, I got  
> the following
> error message: Intially, I tried to double the other Mn position,  
> then tried to
> increase by 50% for both cases i was getting same error. But When I  
> gave the
> following positions for Mn (which actually is not the correct one)
>     Mn 0.25 0.25 0.25
>         0.75 0.75 0.75
> It works, I do not know why? Because these positions are not the  
> correct ones.
>
> Here is the ERROR message:
>
> hkinp: ERROR -
>   When nsppol==1 and nspden==2, at least one of the symmetry  
> operations
>   must be anti-ferromagnetic (symafm=-1), in order to deduce the  
> spin-down
> density
>   from the spin-up density.
>   However, it is observed that none of the symmetry operations is
> anti-ferromagnetic.
>   Action : Check the atomic positions, the input variables spinat,  
> symrel,
> tnons, symafm.
>            In case your system is not antiferromagnetic (it might be
> ferrimagnetic ...),
>            you must use nsppol=2 with nspden=2 (the latter being the default
> when nsppol=2).
>
>    Please, let me know what is wrong with my input file given below:
>
> # Optimization of latice constant for cubic YMnO3 with Spin polarized
> #(Ferromagnetic) conditions
> ndtset 1
> #Optimization of the lattice parameters
>
> optcell 1
> ionmov 3
> tolmxf 5.0d-4
> dilatmx 1.1
> ecutsm 0.5
> nband 64
> nsppol 1
> nspden 2
> nspinor 1
> spinat 0 0 0
>        0 0 0
>        0 0 -4
>        0 0 4
>        0 0 0
>        0 0 0
>        0 0 0
>        0 0 0
>        0 0 0
>        0 0 0
>
> #Definition of the k-point grids
> kptopt 1
> nshiftk 1
> shiftk 0.0 0.0 0.0
> ngkpt1 6 6 6
> getwfk -1
>
> #Definition of the unit cell
>
> acell 3*3.90 angstrom
>
> rprim
> 1 0 0
> 0 1 0
> 0 0 1
>
> #Definition of the atom types
> ntypat 3
> znucl 39 25 8
> #ziontypat 11 15 6
>
> #Definition of the atoms
> natom 10
> typat 1 1 2 2 3 3 3 3 3 3 # 1=Y 2=Mn 3=O
> xred 0.00 0.00 0.00 #Y
>      0.25 0.25 0.25   #Y
>      0.50 0.50 0.50  #Mn
>      0.75 0.75 0.75  #Mn
>      0.50 0.50 0.00  #O
>      0.75 0.75 0.00 #O
>      0.50 0.00 0.50 #O
>      0.75 0.00 0.75 #O
>      0.00 0.50 0.50 #O
>      0.00 0.75 0.75 #O
> #Definition of the planewave basis set
> ecut 30.0
> #Definition of the SCF procedure
> nstep 500
> toldfe 1.0d-6
> diemac 2.0      
>
> Thanks and regards
> SKORLANS K M (MS Student)
> Dept.of Physics National Institute os technology India