On Dec 23, 2009, at 20:52 , Nicki Frank Hinsche wrote: > For my isolating system the Fermi energy would be in the gap, > therefore there wont be an eigenvalue for given k-points at the Fermi > energy. If I shift the energy to a value right where states are, then > I would expect of course some contribution to an iso-energetic > surface. But how to change this 'Fermi energy' in the right way. Is it > enough to change the parameter in input_FS? Of course I know, that the > system isn't charge-neutral anymore after artificially shifting the > Fermi energy.
input_FS is the file containing input data for the program (written by Eyvaz) that calculates the Fermi surface, given the band structure calculated in a previous run, IIRC. That code requires in input the Fermi energy (it might read it from the bands data, but apparently it doesn't). If this is your problem: you can change the Fermi at will, since the band structure is fixed. You can change the Fermi energy in a self-consistent way by adding or removing charge to the system (variable "nelec"). This will modify the band structure wrt the neutral case, but not by much if you add or remove just a fraction of an electron. The code will take care of adding a neutralizing background (needed in order to have a finite value of the energy). Paolo --- Paolo Giannozzi, Dept of Physics, University of Udine via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
