[Wien] large deviation of atomic volume in BiNi compound

[Tomas Kana]

Dear Wien2k users,


I came across a problem with equilibrium atomic volume of 

the BiNi compound. The experimental lattice is hexagonal 


with a = 4.079 Angstroem, c = 5.359 Angstroem 


(P. Villars, Pearson's Handbook: Crystallographic Data for Intermetallic 
Phases)

However, the equilibrium volume turns out to be more 


than 16 % higher than the experimental one. 


I wonder since the equilibrium volume of 


pure Bi and Bi3Ni comes out with much better agreement with 


experiment (about 4 to 5 % deviation). 

I used GGA (no spin orbit coupling), 
Rmt*Kmax = 8.8, lmax = 10, Gmax = 16,  5000 k-points in the 


whole Brillouin zone. I enclosethe structure file in attachment. 


I tried LDA that gives better agreement with experiment 


(about 10 % deviation)  but I think this is still too much.  I have tried 


to use gaussian smearing instead of the tetrahedron method,

increase Rmt*Kmax to 11, increase k-points to 20 000 in the whole 
Brillouin zone but nothing helped. 
In the mailing list I found someone had similar problem with a more 
complicated structure containing bismuth, but that was not solved:
http://www.mail-archive.com/wien%40zeus.theochem.tuwien.ac.at/msg10479.html
Do you have any idea? 
Thank you in advance 
With best regards 
Tomas Kana 
Institute of Physics of Materials,
Academy of Sciences of the Czech Republic 
Brno, Czech Republic 
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BiNi hP4                                                                       
H   LATTICE,NONEQUIV.ATOMS:  2 194_P63/mmc                                     
MODE OF CALC=RELA unit=bohr                                                    
  7.708193  7.708193 10.127043 90.000000 90.000000120.000000                   
ATOM  -1: X=0.00000000 Y=0.00000000 Z=0.00000000
          MULT= 2          ISPLIT= 8
      -1: X=0.00000000 Y=0.00000000 Z=0.50000000
Bi1        NPT=  781  R0=0.00000500 RMT=    2.5000   Z: 83.0                   
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM  -2: X=0.33333333 Y=0.66666667 Z=0.25000000
          MULT= 2          ISPLIT= 8
      -2: X=0.66666667 Y=0.33333333 Z=0.75000000
Ni1        NPT=  781  R0=0.00005000 RMT=    2.2000   Z: 28.0                   
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
  24      NUMBER OF SYMMETRY OPERATIONS
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