Hi, Alice Runi's thesis from 1997 talks about macroscopic averages at interfaces, in chapter 5.
http://www.sissa.it/cm/thesis/1997/ruini.ps.gz maybe a good starting point. -Nick On Mon, 26 Apr 2010, Stefano Baroni wrote: > > On Apr 26, 2010, at 8:41 AM, Gabriele Sclauzero wrote: > > > > wulilixiangguo at sina.com wrote: > I read below and have a question about > macroscopic averages. If my > > system have a surface between two materials which > have different lattice > > constant. > > > Do you mean an interface? (I would say a "surface" only if > one of the two "materials" is > vacuum, but maybe I'm pedantic...) > > How to set the awin? > > Not sure of this, but I think that it is not a good idea to > use macroscopic averages when > there is a change in the periodicity. For instance, in a > recent paper by Singh-Miller and > Marzari (PRB, 2010) it has been reported that the technique > is not well suited for slab > geometries when you account for the relaxation of the > distances between layers. > > > How to macroscopic it twice? > > Maybe I don't understand this point. > > You could run the program twice, with two different window > sizes, in order to match the > two different lattice spacings, but then I don't know if > there is a way to give a > meaningful interpretation to the data at the interface. > > > What you propose, Gabriele, is perfectly legitimate and has been done > indeed af few times in the good ol' times when macroscopic averages had > been invented. I do not remember by heart the reference, but somebody may > want to try a bibliographic search with "resta" and "baroni" as authors > and select the title(s) that may suggest the investigation of lattice > mismatched interfaces. > > SB > > --- > Stefano Baroni - SISSA??&??DEMOCRITOS National Simulation Center - > Trieste > http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) / > stefanobaroni (skype) > > La morale est une logique de l'action comme la logique est une morale de > la pens?e - Jean Piaget > > Please, if possible, don't??send me MS Word or PowerPoint attachments > Why? See:??http://www.gnu.org/philosophy/no-word-attachments.html > > > > > > > > > ***************************************** Nicholas E. Singh-Miller Prof. Marzari Group (quasiamore.mit.edu) Materials Science and Engineering Massachusetts Institute of Technology 13-4066 (617)324-0372 *****************************************
