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[Masayoshi Mikami <mmikami@rc.m-kagaku.co.jp>]

Dear Ms. Dutta,

I might have some comments from another perspective:

1) polar semiconductor surfaces, i.e. GaAs (100).
K.Shiraishi: Journal of the Physical Society of Japan
Vol.59 No.10, October, 1990 pp.3455-3458
http://jpsj.ipap.jp/link?JPSJ/59/3455/
In your case,  you might need double-sized surface
(i.e. both sides can be regarded as "front"),
without relying "H"-terminations etc...
(Sounds heavy task, indeed.)

2) in highly ionic systems, such as MgO :
polar surfaces (e.g. (111)) tend to facet to structures
containing non-polar planes (e.g. (100)).
A typical example (photo) may be found in
V.E.Henrich, Surf. Sci.57, 385-392 (1976).
(the following book might also be interesting:
"The Surface Science of Metal oxides",
by V.E.Henrich and P.A.Cox, Cambridge Univ.Press
I took the above reference from this book.)
So, in your CeO2 (CaF2-type ?), non-polar surfaces
might be more preferred in real life ... !?

In any case, Ce potential would be significant.
Before starting the surface calculations,
some check might be needed for bulk CeO2,
such as the reproducibility of the equilibrium structure...

Best wishes,
Masayoshi

On 2004/02/24, at 15:01, Ms Gargi Dutta wrote:

>   Hi,
>      i am an Abinit user. I am doing a surface calculation of CeO2, in
>    which i have layers of Ce and O alternating , and terminating with
>    Ce layer on one end and O layer on the other end. Hence the system
>    has a depolarization field which needs to be corrected.
>            I don't know how to introduce an artificial electric field
>    in the vacuum region in order to cancel the depolarization field.
>            I am not able to figure out the 'input variables' for the
>    above purpose.
>
>  regards,
>  Gargi