From owner-chemistry- at -ccl.net Sun Aug 28 22:27:37 2005 From: "CCL" To: CCL Subject: RE: slabs and supercells X-Original-From: "Ojwang, J.G.O." content-class: urn:content-classes:message Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="Windows-1252" Date: Mon, 11 Jul 2005 17:10:48 +0200 MIME-Version: 1.0 Sent to CCL by: "Ojwang, J.G.O." [j.g.o.ojwang[a]tue.nl] I'll be brief and to the point, plus use a layman's language. When you want to study the surface of a material then the pragmatic way to go is to terminate one part of a periodic crystal thus creating a slab. We view slab as a structure whose periodicity has been terminated along one direction, that direction being treated as the surface of the crystal. In the case of supercells....a supercell is in simple words a build up of a primitive cell along the three crystallographic axes by addition of more atoms. Supercells are important in the study of defects and dopants. Clearly when you dope a material it is only by a few percentage and as such if you want to be as exact as possible in treating a problem pertaining to defects and doping then you must build a supercell. I hope that answers your questions without much of the jargons used in the field. Ojwang JGO. More contributions are welcome -----Original Message----- From: CCL [mailto:owner-chemistry[a]ccl.net] Sent: Mon 7/11/2005 2:08 PM To: Ojwang, J.G.O. Cc: Subject: CCL: slabs and supercells Sent to CCL by: may abdelghani Hello, CCLer What we mean by slabs and supercells, and why we study them? best regards ___________________________________________________________________________ Appel audio GRATUIT partout dans le monde avec le nouveau Yahoo! Messenger Téléchargez cette version sur http://fr.messenger.yahoo.com