Re: [SIESTA-L] Fermi level and k-grid

2007-01-11 Thread Andrei Postnikov
On Wed, 10 Jan 2007, Oleksandr Voznyy wrote: | The Fermi level is normally calculated by setting the cumulative occupation | number of all bands to the number of valence electrons. | | As I understand this means that Ef in semiconductor would always be | at the VBM and not in the middle of

Re: [SIESTA-L] Fermi level and k-grid

2007-01-11 Thread Oleksandr Voznyy
The Fermi level is normally calculated by setting the cumulative occupation number of all bands to the number of valence electrons. As I understand this means that Ef in semiconductor would always be at the VBM and not in the middle of the gap? How it could happen that Ef appeared somewhere

Re: [SIESTA-L] Fermi level and k-grid

2007-01-10 Thread Andrei Postnikov
On Wed, 10 Jan 2007, Oleksandr Voznyy wrote: | Hi, | till recently I though that checking the convergence of total energy vs k-grid | cutoff is enough. | However, now I've found that while total energy can be very well converged, | Fermi level position is not, and requires at least twice denser

[SIESTA-L] Fermi level and k-grid

2007-01-10 Thread Oleksandr Voznyy
Hi, till recently I though that checking the convergence of total energy vs k-grid cutoff is enough. However, now I've found that while total energy can be very well converged, Fermi level position is not, and requires at least twice denser k-grid (and ~4 times more time). Here is my example