[Pw_forum] Changing Kinetic Energy cut-off

[Giovanni Cantele]

Dear Elliot,

the answer could be: generally speaking, results should change not so much because energy differences are known to converge quite rapidly with respect to the cutoff . However, no answer could be given without more details.

Indeed, the change of the properties with respect to ecutwfc/ecutrho strongly depends on the pseudo potential. So: which elements you are
dealing with? Which type of pseudo potentials? Norm conserving or ultrasoft? In any case tests would be needed.

Giovanni



> On 06 Jul 2015, at 00:22, Elliot Menkah <elliotsmenkah at yahoo.com> wrote:
> 
> Hello Everyone,
> How does or to what extent does changing your ecut along with ecutrho
> affect evaluation of results from computations?
> For instance if you used 60Ry to compute 'delta H' for reactants and you
> use 40Ry to compute 'delta H' for products.
> 
> Reduction to 40 Ry was because some jobs with 60 Ry took too long a time
> only not to converge even after 100 iterations.
> 
> Thank you.
> 
> Kind Regards,
> Elliot
> 
> -- 
> Elliot S. Menkah
> Research Student - Computational Chemistry/ Computational Material Science
> Theoretical and Computational Chemistry
> Dept. of Chemistry
> Kwame Nkrumah UNiversity of Sci. and Tech.
> Kumasi
> Ghana
> 
> Tel: +233 243-055-717
> 
> Alt Email: elliotsmenkah at gmail.com
>           elliotsmenkah at hotmail.com
> 
> 
> 
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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