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

Hi,

At least your input file looks OK.
You could also use the "getcell" input variable to start  from the
last compressed cell. Or if you already have estimation of the bulk
modulus of your material you can also set manualy acell in agreement
with the pressure to gain some time.

Just beware that the smallest the cell (the higher the pressure) the
less accurate is the k-point sampling.

Best,

PMA

On 10/21/07, laurent.pedesseau@insa-rennes.fr
<laurent.pedesseau@insa-rennes.fr> wrote:
>
> Dear Abiniters,
>
> I am trying to find the lattice parameter for a FCC crystal at a given 
> hydrostatic pressure P.
>
> Here is my input guess for doing that so is that correct?
> Or, Is there an other way to get it?
>
> Regards,
>
> Laurent PEDESSEAU
>
> PostDoc SANDIE network
> FOTON-INSA RENNES, France
>
>
>
> # Crystalline InAs
> #
> # Hydrostatic Pressure variation
>
> ndtset 20
>
> #usual self-consistent calculation
> kptopt 1          # Option for the automatic generation of k points,
>                   # taking into account the symmetry
> nshiftk 4
> shiftk  0.5 0.5 0.5
>         0.5 0.0 0.0
>         0.0 0.5 0.0
>         0.0 0.0 0.5
> ngkpt  8 8 8
> toldfe  1.0d-6
>
> getwfk -1
>
> # Hydrostatic Pressure from 0GPa to 10GPa by step of 0.5 GPa
> strtarget:   3*0.0 3*0.0
> strtarget+   3*-0.000016994644613600075 3*0.0
>
>
> #Definition of the unit cell
> ixc 7
> optcell 1
> ionmov  3
> ntime  1500
> dilatmx 1.1
> ecutsm  0.5
> acell: 3*11.3
> acell+ 3*-0.03
>
> rprim  0.0  0.5  0.5   # FCC primitive vectors (to be scaled by acell)
>        0.5  0.0  0.5
>        0.5  0.5  0.0
>
> #Definition of the atom types
> ntypat 2
> znucl 49 33
>
>
> #Definition of the atoms
> natom 2
> typat 1 2
> xred
>
>   0.0  0.0  0.0
>   0.25 0.25 0.25
>
> ecut 35.0
>
> #Definition of the SCF procedure
>
> nstep 1500          # Maximal number of SCF cycles
> diemac 15.15
>


-- 
Pierre-Matthieu Anglade