[Pw_forum] Why there difference between my results and those reported.

[张 洪彬]

Dear everyone:
  I want to calculate band structure of MgB2, which is a superconductor, 
however what I got by pwscf is not the same with those reported in, for 
example, PRB86,4656, which follows the LAPW method. However, those results 
got from PP-PW methods are the same as that of LAPW method. Thus I want to 
know why there are differences and how can I get a reliable electronic 
structure which may be used to analyse to get properties of materials? And 
further more why I can't use pseudopotentials in format of .fhi, and will 
there be any differece in the results with different PPs?
  Thank you in advance.
Here is my input file for MgB2:
 &CONTROL
                 calculation = 'scf' ,
                restart_mode = 'from_scratch' ,
                      outdir = '/pwscf/tmp/' ,
                  pseudo_dir = '/pwscf/pseudo/' ,
                      prefix = 'mgb' ,
                     tstress = .true. ,
                     tprnfor = .true. ,
                     tefield = .false. ,
 /
 &SYSTEM
                       ibrav = 4,
                   celldm(1) = 5.829996,
                   celldm(3) = 1.14100,
                         nat = 3,
                        ntyp = 2,
                     ecutwfc = 30.0 ,
                        nbnd = 8,
                 occupations = 'tetrahedra' ,
 /
 &ELECTRONS
                    conv_thr = 1.0d-8 ,
                 mixing_beta = 0.7 ,
             diagonalization = 'cg' ,
 /
ATOMIC_SPECIES
   Mg   24.30500  Mg.pz-bhs.UPF 
    B   10.81100  B.pz-bhs.UPF 
ATOMIC_POSITIONS alat 
   Mg      0.000000000    0.000000000    0.000000000    
    B      0.500000000    0.288680000    0.570500000    
    B      0.000000000    0.577350000    0.570500000    
K_POINTS automatic 
  30 30 30   1 1 1

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