The ABINIT Users Mailing List ( CLOSED )

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

Hi,

First of all, it may be usefull to check your pseudopotentials. Some
of them gives pretty strange properties for some elements.
Second, be sure that other parameters such as bands, xred and kpts are
converged/within acceptable bounds/correct.
Third, instead of trying to do the computation manualy, you'd better
use optcell (4,5,6) . It will tell you the optimum value of a. And
then you may get more informations about what's happening in your
computation.

regards

PMA



On 4/26/07, taoj0003@ntu.edu.sg <taoj0003@ntu.edu.sg> wrote:
> hi,guys
>
> i m trying to optimize the lattice constant of rutile tio2. i m doing it in 
> this way,
> first, fix c=2.958 as experiment value, and then vary the 'a' from 4.55 to 
> 4.65 with a step 0.01,  the experiment value of 'a' is around 4.59.
> i am looking the Etotal energy, hope the energy reach a min value at around 
> 4.59. However, the result show the Etotal energy always decrease, meaning to 
> take a optimized 'a' value,we need always inrease the value, which go very 
> far from the experiment value.
> The ecut off energy i m using is 120 Hartree, should be quite good enough.
>
> So any one can help me figure out the reason? thanks in advance.


--
Pierre-Matthieu Anglade