The ABINIT Users Mailing List ( CLOSED )

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

Dear Bo Liu,

> I am trying to study the properties of defect such as oxygen vacancy.
> But I am not clear how to set xred for a oxygen vacancy, just simply 
> remove
> the oxygen?

Yes, just remove the oxygen.

> and how to deal with the charged vacancy (such as 1+,2+,1-,2-)?
> Can I put an electron at the vacancy site ? if so , how to do that?

http://www.abinit.org/Infos_v4.6/vargs.html#charge
(NB: see also, http://www.abinit.org/Infos_v4.6/varint.html#nelect )
Defect levels induced by oxygen vacancy will appear somewhere
in band gap (assume the system is insulator ...),
The number of electrons of the defect levels will change
by setting the option "charge"... e.g. suppose a wide gap, ionic oxide.
The oxygen vacancy level will appear in the gap.
The neutral state may be occupied by two electrons.
By setting "charge +2", the defect level will lose the two electrons
so that it will be of +2 charge state ... and so on.
If the system has covalency (such as SiO2), discussion will not be
so straightforward as the above example. Several defect levels
may appear in the gap...

Some discussion about the option "charge" may be found
in the forum ML archive. And also, there should be many relevant papers.

Good luck,
Masayoshi