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["Anglade Pierre-Matthieu" <anglade@gmail.com>]

Hello,

I personnally do not have any such examples. 
It is possible that someone else on the forum has. 
You should know that there is a very nice source of examples for abinit. This is the automated tests directory. Since they tests every feature of Abinit you may find there what you are looking for. To search for examples people generally uses "grep" on the various input (*.in) files and README.

regards,

PMA

On 8/13/07, farah marsusi <fmarsusi@yahoo.com> wrote:

Hello prof.Matthieu

Thank you very much for answering my question. I down loaded the notes.Do you have any example for calculating electron affinity and ionization potential in molecules.

very thanks

F.Marsusi

Anglade Pierre-Matthieu <anglade@gmail.com> wrote:

Hi,
Since many have asked for those notes I have put them online here :
http://anglade.googlepages.com/idealeaguesummerschool2007
If you read this, let me know about your comments.

About your problem with H20:
1) Energies you get in DFT code are not absolute. What is meaningfull
is differences of total energies between systems. For instance I'm
prety sure that what you would have like to consider is the difference
between the energies of your three atoms isolated and that of your
molecule. To get It you must compute the energy of the isolated H
atom: EH; that of Oxygen EO and that of the molecule EH20. Then you
can compare
EH2O-2*EH-EO between codes.

2) For each of the code you must make sure the computation is
converged. For instance in the extract of input you give, it is almost
sure that the ecut is not converged.

Best,

PMA

On 8/12/07, farah marsusi wrote:
>
> Hello Dr. Anglade
> could you please send this pdf text for me too.I am abinit new user . I run both abinit and G03 (B3LYP functional with 6-31G* basis)for H2O molecule ,but the total energy were different. G03 calculated about 76Ha and abinit about 14Ha.I don't know why?
> Herer is my input file.
> thanks
> F.Marsusi
>
> acell 3*30.0 angst
> ntypat 2
> natom 3
> ntypat 1 2 2
> znucl 8 1
> xangst
> 0.000000 0.110843 0.000000
> 0.783809 -0.443452 0.000000
> -0.783809 -0.443294 0.000000
> nkpt 1
> ecut 200 ev
> ixc 11
> toldfe 5.0d-8
>

> Anglade Pierre-Matthieu wrote:
> Hi
>
> There is no such "true" ecut:
> the cutoff energy describes how many plane waves wil be used to
> describe the wave functions within your calculations. The more plane
> waves the more frequencies will be depicted and then the more accurate
> will be your calculation.
> You have to find an equilibrium between the computation time and the
> accuracy of your calculation. That's why we usually search the minimum
> ecut that accurately describe the system. Here "accurately" may
> strongly depends on the properties you want to examine. If you have no
> special requirement an absolute convergence of about 1e-3 Ha is
> usually considered correct because pseudopotentials tends to reproduce
> the full electron calculation on which they are based to this
> precision. That is, you will (almost) never get more physics by having
> something better converged. However some problems may require
> convergency of ecut down to 1e-4 or 1e-5 Ha.
>
> You can find examples of how to find the correct value of ecut in the
> Abinit tutorials. HAve you tryed them and reproduce the steps depicted
> there in your calculations ? If you want some comments on your own
> results, please send some details about your input and output.
>
> Also, I'm just back from a summer school where I have presented
> Abinit to very beginners in DFT - PW calculations. Then, I have lots
> of didactical materials where I insist on this very problem. If you
> like I can send those PDF to you.
>
> regards
>
> pierre-matthieu Anglade
>
> On 8/2/07, m_mousavi1980@yahoo.com wrote:
> >
> > Hi
> >
> > I have a question
> > How can i understand which ecut for zno is true.
> > I get ecut 62.01
> > thanks
> > best regard
> >
>
>
> --
> Pierre-Matthieu Anglade
>
>
>
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