[Pw_forum] charge state

[Nicola Marzari]

ali kazempoor wrote:
> Dear users
> In simulation of charged defect in bulk  ,makov-payne correction are 
> used. But the terms that add to correct the total energy need to count 
> madeulun constant. I study TiO2 in tetragonal cell( the size of cell is 
> 2*2*3). How can I obtain madeulung constant?
> thanks  a lot

Charged defects in the bulk are fairly tricky - you could use
(I presume) a Makov-Payne correction using the dielectric constant of
TiO2, abut you still need to make sure you have some absolute reference
(e.g. the average of the electrostatic potential away from the defect).

I believe there is quite a lot of recent literature (e.g. PA Schultz);
note also that the second term in original Makov-Payne correction is
not correct - see Dabo et al PRB 77, 115139 (2008).

			nicola

---------------------------------------------------------------------
Prof Nicola Marzari   Department of Materials Science and Engineering
13-5066   MIT   77 Massachusetts Avenue   Cambridge MA 02139-4307 USA
tel 617.4522758 fax 2586534 marzari at mit.edu http://quasiamore.mit.edu