The ABINIT Users Mailing List ( CLOSED )

[matthieu verstraete <matthieu.jean.verstraete@gmail.com>]

PMA is correct as always (especially when it comes to convergence),
but this does remain a little confusing for beginners - there is no
need to change diemac. I'll see if I can change the tutorial material
(Xavier?).

Matthieu

On Sun, Jun 14, 2009 at 9:59 PM, Anglade
Pierre-Matthieu<anglade@gmail.com> wrote:
> Hi,
>
> There is not much differences between diemac = 1 (means no
> preconditionning at all) and diemac = 2 (means that the residuals
> changes of the largest G vector will be divided at most by two). Yet
> both are quite different from the default diemac = 1e6 which divide
> the residual of the largest G vectors by 1e6.
>
> Note that diemac influence only the rate of convergence. Whatever its
> value, if your calculation converge to the single ground state, it
> will give the same results whatever the value of diemac.
>
> Does this answer your question ?
>
> regards
>
> PMA
>
> On Sun, Jun 14, 2009 at 1:09 AM, Rob<spamrefuse@yahoo.com> wrote:
>>
>> Hi,
>>
>> I'm using 5.7.4 with the corresponding Tutorials.
>>
>> The variable diemac is rather confusing to me and
>> hence I 'blindly' follow the guidelines of the user guide.
>>
>> In Tutorial 1 and 2, on the H2 molecule, all the given input
>> files have diemac = 2, as is recommended by the guidelines.
>> However, only in lesson 1.5 suddenly the diemac is 1.
>> Is this a typo in the t15.in input file, or is this intentionally?
>>
>> If it's intentionally, it needs an explanation as to why diemac
>> must change in this case.
>>
>> Thank you!
>>
>> Rob.
>>
>>
>>
>>
>
>
>
> --
> Pierre-Matthieu Anglade
>



-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Matthieu Verstraete

European Theoretical Spectroscopy Facility (ETSF)
Dpto. Fisica de Materiales,
U. del Pais Vasco,
Centro Joxe Mari Korta, Av. de Tolosa, 72,   Phone: +34-943018393
E-20018 Donostia-San Sebastian, Spain        Fax  : +34-943018390

Mail : matthieu.jean.verstraete@gmail.com
http://www-users.york.ac.uk/~mjv500