[Pw_forum] problem in calculating the binding energies with pwscf

[Giuseppe Mattioli]

Dear Jorg
Calculations of isolated atoms may sometimes be tricky.
Try to have a look at

/yourespresso/examples/example11

HTH

Giuseppe


On Thursday 21 July 2011 15:06:31 Jörg Buchwald wrote:
> Hello,
> I'm performing some first test-calculations with pwscf, where I try to
> get the binding energy of bulk silicon. The problem is, that the
> resulting energy, which should be the difference of the total
> energy of silicon crystal structure and the a free atom, is about 3eV
> too low. I used different pseudopotentials, different
> lattice-parameters and I also tested the convergencies (with k and
> the energy-cut-off) which worked, but I don't have a clue what a made
> wrong.
>
> Here are my Input files:
>
> ---
>  &control
>     prefix='silicon',
>     pseudo_dir='/home/joerg/espresso-4.3.1/pseudo'
>     outdir = '/home/joerg/scratch',
>  /
>  &system
>     ibrav=  2, celldm(1) =10.263142, nat=  2, ntyp= 1,
>     ecutwfc = 30.0,
>  /
>  &electrons
>  /
> ATOMIC_SPECIES
>  Si  28.086  Si.pbe-n-van.UPF
> ATOMIC_POSITIONS
>  Si 0.00 0.00 0.00
>  Si 0.25 0.25 0.25
> K_POINTS automatic
>  9 9 9 1 1 1
> ---
>
> and for the free atom:
>
> ---
> &control
>     prefix='silicon',
>     pseudo_dir='/home/joerg/espresso-4.3.1/pseudo'
>     outdir = '/home/joerg/scratch',
>  /
>  &system
>     ibrav=  0, celldm(1) =50.2, nat=  1, ntyp= 1,
>     ecutwfc = 80.0,occupations='fixed',starting_magnetization(1)=10,
>  /
>  &electrons
>  /
> ATOMIC_SPECIES
>  Si  28.086  Si.pbe-n-van.UPF
> ATOMIC_POSITIONS
>  Si 0.50 0.50 0.50
> K_POINTS gamma
>
> CELL_PARAMETERS {cubic}
>     1.00 0.00 0.00
>     0.00 1.00 0.00
>     0.00 0.00 1.00
> ---
>
> It would be nice if someone could help me.
> Thx & regards,
> Jörg Buchwald
>
>
> Leibniz-Institut fuer Oberflaechenmodifizierung e.V.
> Permoserstrasse 15
> 04318 Leipzig
> GERMANY
>
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   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
   v. Salaria Km 29,300 - C.P. 10                
   I 00015 - Monterotondo Stazione (RM)          
   Tel + 39 06 90672836 - Fax +39 06 90672316    
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