Hi Eduardo, Thanks for your reply.
I read the papers referred in the links. But I could not understand which step I am missing in my calculation. For a surface surface calculation there should not be any potential shift. Average electrostatic potential in the bulk is not coming into the picture of calculating WF, I guess. Only thing that is needed to be considered is the energy difference between vacuum level and Fermi level. I made sure that I was choosing correct options (surface, potential, filter function length etc.) in macroave.in file. Plotting the *.PAV gives me the vacuum level. As I said I checked the convergence of the WF (E_c - E_f) as function of slab and vacuum thicknesses. So, the only place that I can make mistakes is probably E_f, which lies in between Ec_min and Ev_max for semiconductors. I dont know if shifting of E_f is necessary or if that's what I need to do. I appreciate any suggestions. Thanks, Zubaer On Wed, Jul 23, 2008 at 7:45 AM, Eduardo Anglada <[EMAIL PROTECTED]>wrote: > Hi, > Please take a look at this previous posting by Javier Junquera. He has > written > a nice review about the subject > > http://www.mail-archive.com/siesta-l@listserv.uam.es/msg00627.html > > Best regards, > Eduardo > > > > On 18/07/2008, at 20:34, zubaer wrote: > > Hi, >> >> I wanted to calculate the workfunction of a Si (001) surface using >> SaveTotalPotential and SaveElectrostaticPotential and then macroave.x >> utility. >> >> I checked the convergence in terms of slab layer and vacuum thicknesses. >> Finding the vacuum level and subtracting the fermi energy obtained from scf >> file, I got the value 5.51eV, which is way higher compared to the >> experimental value of 4.85eV. >> >> Could you suggest what things I need to check to make a better estimate. >> >> I appreciate any helps. >> >> Thanks, >> Zubaer >> >> >>
