[Pw_forum] binding energy

[Giovanni Cantele]

1) maybe providing at least the inputs of the total, species1 and species2 runs would help

2) is E_{species1} the energy of the whole  cluster without the ligand?

3) what are the cell sizes and k-point grids used in the three calculations?

4) please kindly provide also your affiliation in posting to this forum, as usually requested

Giovanni

> On 28 Nov 2016, at 12:03, Moosavi Seyed Mohamad <seyedmohamad.moosavi at epfl.ch> wrote:
> 
> Hi 
> 
> I calculated the binding energy of a cluster (species1) with a ligand(species 2) with this formula:
> E_{total} - E_{species1} - E_{species2}
> 
> I run PAW in a cubic cell large enough to avoid periodicity effects in the calculations (10 angstrom each side).
> The geometry converges very well to a 2.1 angstrom distance between species, as we expected.
> 
> However, the results are surprising from two respects.
> First, the binding energy is too high. ~500 kcal/mol
> 
> Second, when I add new monomer to species2 (make a dimer), in principle, the binding energy should remain constant (The bond length remains the same).
> However, I get extra ~200kcal/mol in the energy.
> 
> The number of electrons:
> cluster (species1): 499
> monomer (species2): 60
> dimer (species2): 102
> 
> So, something should be wrong with the formula or a scaling factor is  needed here.
> I am wondering if you can guide me through this.
> 
> Best regards
> Mohamad
> 
> 
> ​
> 
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-- 

Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: giovanni.cantele at spin.cnr.it
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: http://people.na.infn.it/~cantele

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