[Pw_forum] Binding energy of Cu at CNT

[chengyu yang]

Thank you, Dr. Giannozzi .

But my question is this:
(1) How could I get the correct binding energy? May I use the  C.pz-vbc.UPF
and Cu.pz-d-rrkjus.UPF potential? Will the choice of potential affect the
final result?
(2) The literature I am reading used the projector-augmented wave(PAW)
potential, and also the electron exchange and correlation is treated by
using the Perdew burke Ernzerhof (PBE) formulation of the generalized
gradient approximation. In fact I cannot find such potentials in all the
pseudo files.
(3) It also used conjugate-gradient algorithm to relax the ions, do we have
this in our QE, or the algorithm are replaceable?

I am sorry to ask, but advice from this forum is important to help.
Thank you.

Best regards.

Chengyu Yang
MMAE,University of Central Florida,US



2011/10/22 Paolo Giannozzi <giannozz at democritos.it>

>
> On Oct 22, 2011, at 19:25 , chengyu yang wrote:
>
> > At first I used ultrasoft potential for both cu and cnt,
> > but the result is about -1.6 ev, much different from
> > around -0.1 ev in the literature.
> >       Then I changed the potential to PAW potential,
> > for that is what's used in the literature
>
> you also changed from LDA to PBE. It's not a minor difference,
> especially if the bonding is weak. Why don't you try a few
> simpler systems to start with?
>
> P.
> ---
> Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
>
>
>
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