The ABINIT Users Mailing List ( CLOSED )

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

Let's analyse your output :
The SCF convergence is OK
much more than 3-6 atoms
awfully high forces (~1 Ha.bohr^-1)
We won't make the convergence test over ecut and k-point but we shall
assume you did.
So 2 solutions :
1) Start from something closer to stability if possible
(looks like there is a problem along x and z axis) could it be an
error in the input ?
2) Try a safer (yet slower) algorithm
ionmov 1
optionally try to increase "vis" and to reduce "dtion" if the total
energy do not decrease.

regards

PMA

On Mon, May 19, 2008 at 8:33 PM, ghada ameereh <ghaddosh@yahoo.com> wrote:
> Dear sir:
> the attached input and output files are above. i did
> optimisation for atomic position in this input as a
> first step.and here i get a lack of convergence.
>
> best wises.
> gada
> --- Anglade Pierre-Matthieu <anglade@gmail.com> wrote:
>
>> Hello,
>>
>> It looks like you forgot your input/output file.
>>
>> If you are sure of the cutoff energy and k-smapling
>> convergence, and
>> if the SCF cycles converges correctly for all your
>> optimisation it is
>> possible that the optimization algorithms of Abinit
>> are not
>> efficiently dealing with your problem. This may
>> happens when your
>> system is  either too far away from relaxation or
>> have too muche
>> degrees of freedom.
>> In the second case it is always recommended to start
>> by optimizing
>> only the atomic position before any structural
>> relaxation.
>> In the other cases the best could be to use damped
>> molecular dynamic.
>> Although slow, as long as the step size is small
>> enough it can lead
>> you close to the ground state.
>>
>> regards
>>
>> PMA
>>
>> On Mon, May 19, 2008 at 4:32 PM, ghada ameereh
>> <ghaddosh@yahoo.com> wrote:
>> > dear abinitor:
>> > i want to calculate electronic properties of
>> > Ni4SiGe3.but in optimization output file we get
>> lack
>> > of convegence (Etot changes continuously ), the
>> input
>> > ,output and psp files are attached.(i began the
>> > optimization with orthorhombic lattice
>> structure).if
>> > you have any information about this problem please
>> > send me and i will appreciate that for you.
>> >
>> > gada
>> >
>> >
>> >
>> >
>>
>>
>>
>> --
>> Pierre-Matthieu Anglade
>>
>
>
>
>



-- 
Pierre-Matthieu Anglade