[Pw_forum] How to choose the supercell ? (cao tengfei)

[Giovani Faccin]

Dear 曹腾飞,

One possibility that comes to my mind is to proceed as follows:

1 - First make a few supercells of pure graphene, each with a different
size, all without the hydrogen atom, and evaluate their total energies per
atom and/or bands, in order to make sure that the cell you'll use on step 2
is large enough to remove spurious border effects.

2 - Once you get a cell that's large enough, then evaluate it with the
hydrogen atom and check the forces acting on the H atom.

3 - Now try to use a larger cell with the hydrogen, and evaluate the forces
again on the H atom.

4 - If the cell is large enough so that no border effects are present and
the hydrogens are not interfering with each other, then the forces on step 2
and 3 should be the same.

Hope it helps.

Giovani M. Faccin
UFMS - Brazil




2011/4/26 曹腾飞 <tfcao at theory.issp.ac.cn>

>  Dear QE users:
> I want to construct a supercell of graphene with one Hydrogen absorbed on
> it , and my question is how can I choose the supercell properly so that the
> interaction between Hydrogens can be neglected . Any suggestions will be
> greatly appreciated .
>
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>


-- 
Giovani
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