[Pw_forum] polarization:5cells of pbtio3

[Jaret Qi]

1.08277316 is c/a for pbtio3, I already did convergence test before run vc-relax, so what scf will add to my structure?

 


     On Friday, September 4, 2015 6:45 PM, stefano de gironcoli <degironc at sissa.it> wrote:
   

  the coordinates and the lattice vectors are given in unit of alat so you need 
 to add 1.08277316 x 1,2,3,4 
 where did you get 1.08 from?
 
 In any case you need to run an scf calculation first. 
 
 stefano
 
 On 05/09/2015 01:39, Jaret Qi wrote:
  
  Hello all, I'm calculating the polarization of 5 cells of PbTiO3, I have set up the one unit cell correctly and got all of the properties in a good agreement as in literature. But when I tried to calculate the polarization of the 5 cells, I got this error when I run the nscf: error: too many bands are not converged, The way I constructed the 5 cells is by adding c/a for the z-components of the 2nd cell, 2c/a for the z-components of the 3rd cell, 3c/z for the z-components of the 4th cell, 4c/a for the z-components of the 5th cell.
 see this: 1cell : 
  ATOMIC_POSITIONS 
 Pb       0.000000000   0.000000000  -0.011923470
 Ti       0.498189800   0.498189800   0.542939650
 O        0.498189800   0.498189800   0.085663538
 O        0.498189800   0.000000000   0.642799807
 O        0.000000000   0.498189800   0.642799807
 
 CELL_PARAMETERS (alat)
    0.996379599   0.000000000   0.000000000
    0.000000000   0.996379599   0.000000000
    0.000000000   0.000000000   1.082777316
  
  5cells: 
  ATOMIC_POSITIONS  
 Pb      0.0000000       0.0000000      -0.01192347
 Ti      0.4981898       0.4981898       0.54293965
 O       0.4981898       0.4981898       0.085663538
 O       0.4981898       0.0000000       0.642799807
 O       0.0000000       0.4981898       0.642799807
 Pb      0.0000000       0.0000000       1.06807653
 Ti      0.4981898       0.4981898       1.62293965
 O       0.4981898       0.4981898       1.165663538
 O       0.4981898       0.0000000       1.722799807
 O       0.0000000       0.4981898       1.722799807
 Pb      0.0000000       0.0000000       2.14807653
 Ti      0.4981898       0.4981898       2.70293965
 O       0.4981898       0.4981898       2.245663538
 O       0.4981898       0.0000000       2.802799807
 O       0.0000000       0.4981898       2.802799807
 Pb      0.0000000       0.0000000       3.22807653
 Ti      0.4981898       0.4981898       3.78293965
 O       0.4981898       0.4981898       3.325663538
 O       0.4981898       0.0000000       3.882799807
 O       0.0000000       0.4981898       3.882799807
 Pb      0.0000000       0.0000000       4.30807653
 Ti      0.4981898       0.4981898       4.86293965
 O       0.4981898       0.4981898       4.405663538
 O       0.4981898       0.0000000       4.962799807
 O       0.0000000       0.4981898       4.962799807
 CELL_PARAMETERS (alat)
    0.996379599   0.000000000   0.000000000
    0.000000000   0.996379599   0.000000000
    0.000000000   0.000000000   5.413886650
  
  Is there any problems with the construction of the supercell? 
   
  
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