next up previous contents index
Next: Orbital optimization Up: Density of states Previous: Conventional scheme   Contents   Index

For calculations with lots of k-points

Since the calculation of density of states (DOS) of a large-scale system with lots of k-points requires a considerable memory size, the post-processing code 'DosMain' for generating the partial and total DOS tends to suffer from a segmentation fault. For such a case, a Gaussian DOS scheme is available in which the partial DOS is calculated by the Gaussian broadening method in the OpenMX on-the fly calculation and the information of wave functions is not stored in the file '*.Dos.vec'. Since this scheme does not require a large sized memory, it can be used to calculate DOS of large-scale systems. Then, you can specify the following keywords in your input file.

     DosGauss.fileout      on       # default=off, on|off
     DosGauss.Num.Mesh    200       # default=200
     DosGauss.Width       0.2       # default=0.2 (eV)
When you use the scheme, specify 'on' for the keyword 'DosGauss.fileout'. And the keyword 'DosGauss.Num.Mesh' gives the number of partitioning for the energy range specified by the keyword 'Dos.Erange'. The keyword 'DosGauss.Width' gives the width, $a$, of the Gaussian $\exp( -(E/a)^2 )$. The keyword 'DosGauss.fileout' and the keyword 'Dos.fileout' are mutually exclusive. Therefore, when you use the scheme the keyword, 'Dos.fileout' must be 'off' as follows:
     Dos.fileout          off       # on|off, default=off
Also, the following two keywords are valid for both the keywords 'Dos.fileout' and 'DosGauss.file'.
     Dos.Erange       -20.0  20.0   # default=-20 20 
     Dos.Kgrid           5 5 5      # default=Kgrid1 Kgrid2 Kgrid3
It should be noted that the keyword 'DosGauss.fileout' generates only the Gaussian broadening DOS, which means that DOS by the tetrahedron method cannot be calculated by the keyword 'DosGauss.fileout'. After the OpenMX calculation with these keywords, the procedure for DosMain is the same as in the conventional scheme.


next up previous contents index
Next: Orbital optimization Up: Density of states Previous: Conventional scheme   Contents   Index
t-ozaki 2013-05-22