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["Erik Ylvisaker" <eylvisaker@physics.ucdavis.edu>]

It looks as though your results are converging.  The number of k-points is 
not a variational parameter, so the total energy can go up or down when it 
is changed.  It is not unusual.

----- Original Message ----- 
From: <coldwind1978@yahoo.com.cn>
To: <forum@abinit.org>
Sent: Sunday, October 16, 2005 7:37 AM
Subject: [abinit-forum] why total energies increase with number of K point 
increasing in BaTiO3?


> Dear all user:
> i have calculte the total energies of BaTiO3 under various k point.
> i found the total energies increase with number of k point increasing, 
> which is different with the tendency in TuTorial wich the energies 
> decrease with number of K point increasing. my pseudopotential is TM 
> potential which is downloaded in abinit web. Furthmore, i found my cell 
> parameter after optimization is lager than the experimental cell 
> parameters within LDA.
> please tell me if my results is incurrate.why the problem appears?
> there is my input file as follows:
> ndtset 5
> iscf   5
> ngkpt1 4 4 4
> ngkpt2 5 5 5
> ngkpt3 6 6 6
> ngkpt4 7 7 7
> ngkpt5 8 8 8
> ecut 35
> #Common data
> kptopt   1
> toldfe   1.0d-12
> acell 3.994 3.994 3.994 angstrom
> angdeg 90 90 90
>  natom   5
>  nband   30
> nshiftk   1
>  nstep   700
> ntypat   3
>  typat   1 2 3 3 3
>   xred  0.0  0.0  0.0
>         0.5 0.5 0.5
>         0.5 0.5 0
>         0.5 0 0.5
>         0 0.5 0.5
> znucl 56 22 8
> diemac 12
> diemix 0.5
> total energy can be found below:
> 3 3 3 -7.17282528491798E+01
> 4 4 4 -7.17263885360737E+01
> 5 5 5 -7.17259943435173E+01
> 6 6 6 -7.17259215384533E+01
> 7 7 7 -7.17259045664537E+01
> 8 8 8 -7.17258929001672E+01