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["D. R. Hamann" <drhamann@mat-simresearch.com>]

Dear Ariesto,

Your mail to the forum did come through, as I remember seeing it a few 
days ago, so I am replying to both you and it.

Your use of the term "semi-infinite system" is not standard.  Some of my 
early work on surface electronic structure was based on a method 
developed for semi-infinite systems (eg., The Electronic Structure of 
Solid Surfaces, J. A. Appelbaum and D. R. Hamann, Rev. Mod. Phys. 48, 
479 (1976)).  The surface model was periodic in two dimensions (say x 
and y) but only filled half of space in the z direction.  There was thus 
no periodicity in the z direction, even though the potential became 
essentially periodic a few layers inside the surface.

What you are talking about, eg. a graphene ribbon, is infinite (and 
periodic) in one dimension and finite in the other two.  As in many 
abinit examples, finite systems can be treated with supercells in which 
the system is modeled as being periodic in all directions, but the cell 
dimensions are chosen to be large enough in the finite directions so 
that there is no coupling between the atoms in adjacent cells in those 
directions.

Abinit cannot handle the semi-infinite surface model described above.  
However, almost all current calculations of surface electronic structure 
use slabs of solid periodically repeated in the surface-normal 
direction, with sufficiently thick "vacuum" layers in between.

Sincerely,
Don Hamann

m_ariesto wrote:
> Dear DR.Hamann,
> I pose a question to you personaly because my mail to forum have been 
> rejected with no clear reason.
> I wonder if abinit can calculate infinite system (i.e, infinite  along 
> one direction,y, but limited by 2 edges along another direction 
> ,x,)like in graphene ribbon (PRB vol:59 page:8271).
> your explanation will be valuable for me.
> sincerely yours,
> Ariesto

--
D. R. Hamann
Mat-Sim Research LLC    | Deptartment of Physics
P.O. Box 742            |  and Astronomy
Murray Hill, NJ 07974   | Rutgers University
phone: 908-370-8079     | 732-445-4381

email: drhamann@mat-simresearch.com