nband in input file and pspatm in log file

Total energy, geometry optimization, DFT+U, spin....

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kello
Posts: 11
Joined: Wed Apr 27, 2011 8:39 pm

nband in input file and pspatm in log file

Post by kello » Fri May 06, 2011 6:12 pm

Hello:

I am new to ABINIT and I have some questions about the input and output files. Problem: I have the phase Ti5Pt3 (16 atoms, hexagonal, P63/mcm) and I want to obtain the best cut-off energy and k-grid (dataset) so then I will use this values to expand the crystal structure to 80 atoms (new phase). Here, I am assuming that these values will be good for this new crystal structure. I run the dataset for 4x4x4 and I varied the ecut from [4:2:20], but at ecut=10 and above the output file said something about the k-points and that I should increase the number of band (before that I let the software to calculate the best nband for Ti and Pt and it was 58). So, I increased to 60. Then at ecut=16, the same thing happened and I increased the nband to 62. How can I approach (solve) this issue?

Second, a paragraph in the log file said:

Code: Select all

pspatm : COMMENT -
  the projectors are not normalized,
  so that the KB energies are not consistent with
  definition in PRB44, 8503 (1991).
  However, this does not influence the results obtained hereafter.
 pspatm: epsatm=   13.02881305


Is this important? is there something that I need to change in the input file? Mi input file is:>

Code: Select all

# Ti5Pt3

#ndtset 9
#ecut: 4    ecut+ 2

getwfk -1         # This is to speed up the calculation, by restarting
                  # from previous wavefunctions, transferred from the old
                  # to the new k-points.

#Definition of occupation numbers
occopt 4          #metallic occupation of levels. Cold smearing of N. Marzari
tsmear 0.05       #broadening of the occupation numbers

#Definition of the unit cell
acell  15.1178 15.1178 9.4486  # hexagonal

rprim   1.0   0.0  0.0                #hexagonal primitive vectors must be
       -0.5   0.866025403784439  0.0  #specified with high accuracy to be
        0.0   0.0  1.0                #sure that the symmetry is recognized
                                      #and preserved in the optimization
                                      #process

#Definition of the atom types
npsp   2           # 2 pseudopotentials
ntypat 2           # 2 type of atoms
znucl  22 78       # The keyword "znucl" refers to the atomic number of the
                   # possible type(s) of atom. The pseudopotential(s)
                   # mentioned in the "files" file must correspond
                   # to the type(s) of atom.
nband 62
                       
#Definition of the atoms
natom 16                # 16 atoms
typat 10*1 6*2         
xred  0.33333333  0.66666667   0.00000000  #Ti1
      0.66666667  0.33333333   0.50000000  #Ti2 
      0.66666667  0.33333333   0.00000000  #Ti3
      0.33333333  0.66666667   0.50000000  #Ti4 
      0.23600000  0.00000000   0.25000000 #Ti5
     -0.23600000  0.00000000   0.75000000 #Ti6   
      0.00000000  0.23600000   0.25000000 #Ti7
      0.00000000 -0.23600000   0.75000000 #Ti8 
      0.23600000  0.23600000   0.75000000 #Ti9   
     -0.23600000 -0.23600000   0.25000000 #Ti10
      0.59950000  0.00000000   0.25000000 #Pt1
     -0.59950000  0.00000000   0.75000000 #Pt2   
      0.00000000  0.59950000   0.25000000 #Pt3
      0.00000000 -0.59950000   0.75000000 #Pt4 
      0.59950000  0.59950000   0.75000000 #Pt5   
     -0.59950000 -0.59950000   0.25000000 #Pt6

#Definition of the k-point grid
ngkpt   4 4 4       # Definition of the different grids
nshiftk 1           # of the reciprocal space. For a hcp
shiftk  0.0 0.0 0.5

#Exchange-correlation functional
ixc 1             # LDA Teter Pade parametrization

#Definition of the planewave basis set
ecut  18.0         # Maximal kinetic energy cut-off, in Hartree

#Definition of the SCF procedure
nstep  70          # Maximal number of SCF cycles
toldfe 1.0d-6     # Will stop when, twice in a row, the difference
                  # between two consecutive evaluations of total energy
                  # differ by less than toldfe (in Hartree)
                  # This value is way too large for most realistic studies of materials


I hope somebody in this forum can help me.

Best Regards,
Karem

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