The ABINIT Users Mailing List ( CLOSED )

[Xavier Gonze <xavier.gonze@uclouvain.be>]

Well, it is likely that your starting acell is very bad. Hence, the
Broyden optimization wants to make a big jump, and the dilatmx
that you specified is too small. Of course you might increase this  
value of dilatmx,
but the suggested value is so large, that it is worth consider
to restart from a better acell.

Good luck,
Xavier

On 05 Apr 2008, at 17:01, youcef wrote:

> dear users,
> I am a biginer abiniter. now I try to stydy NaMgH3 and the relative  
> enthalpie
> of formation :
> 1- for NaMgH3 the relaxation and the optimization of volume (celle  
> parametres )
> with abinit go fine ( no probleme in the Scf cycles).
> 2-but when  i do the same thing (structure optimization) for NaH  
> using this
> input file:
> #structure et energie total de NaH
> #Definition de la maille elementaire
> #**********************************
>    acell 4.8900 4.8900 4.8900 angstrom
> #   angdeg 90.0 90.0 90.0
> rprim 1.0 0.0 0.0
>       0.0 1.0 0.0
>       0.0 0.0 1.0
> #Definition des atomes
> #*********************
>    natom 2
>    ntypat 2
>    znucl 11 1
>    typat 1 2
>    xred  0.00000000 0.00000000 0.00000000
>          0.50000000 0.50000000 0.50000000       
> ## geom part ends ##
> ixc 11
> #Definition de la procedure scf
> #******************************
> iscf 7
> nstep 200
> #Definition de la base d'ondes planes
> #************************************
> ecut 50
> ngkpt 8 8 8
> kptopt 1
> #Structural relaxation
> ionmov 2
> optcell 1
> ecutsm 0.5
> #Structural relaxation
> ntime 30
> dilatmx 1.05
> #*********************
>    toldfe 1.0d-07
> ****************
> the output in the end (3 lignes):
> At the end of Broyden step  1, total energy= -9.89981836322699E-01 Ha.
>  BROYDEN STEP NUMBER   2
> ------------------------------------------------------
>      iter   Etot(hartree)      deltaE(h)  residm     vres2     
> diffor	maxfor
> *****
> So its clear that the calculations stop after two cycle.
> In the end of log file there is:
> BROYDEN STEP NUMBER   2   
> ------------------------------------------------------
>  Unit cell characteristics (before scfcv) :
>   acell=  2.9555905615E+01  2.9555905615E+01  2.9555905615E+01
>   rprim=  1.0000000000E+00  0.0000000000E+00  0.0000000000E+00
>           0.0000000000E+00  1.0000000000E+00  0.0000000000E+00
>           0.0000000000E+00  0.0000000000E+00  1.0000000000E+00
>   ucvol=  2.5818607361E+04 Bohr^3
>
>   xred=
>   0.0000000000E+00   0.0000000000E+00   0.0000000000E+00
>   5.0000000000E-01   5.0000000000E-01   5.0000000000E-01
>  Cartesian coordinates (bohr)
>   0.00000000000000E+00  0.00000000000000E+00  0.00000000000000E+00
>   1.47779528076982E+01  1.47779528076982E+01  1.47779528076982E+01
>  Cartesian forces (hart/bohr); max,rms= 0.00000E+00 0.00000E+00  
> (free atoms)
>   0.00000000000000E+00  0.00000000000000E+00  0.00000000000000E+00
>   0.00000000000000E+00  0.00000000000000E+00  0.00000000000000E+00
>
>
>      iter   Etot(hartree)      deltaE(h)  residm     vres2     
> diffor	maxfor
>
>  chkdilatmx: ERROR -
>   The new primitive vectors rprimd (an evolving quantity)
>   are too large with respect to the old rprimd and the accompanying  
> dilatmx :
>   this large change of unit cell parameters is not allowed by the  
> present value
> of dilatmx.
>   You need at least dilatmx=    3.198429E+00
>   Action : increase the input variable dilatmx.
>
>  leave_new : decision taken to exit ...
> **
> what is wrong in my input file?
> thank you for your help