Hi Giovanni, thanks a lot for your quick reply. I guess you are definetely right, I did not recognize such error. I will put right way the calculation of the surface allowing the relax of all the atoms. I will let you know the results.
By the way, do you think that the dipole correction is always necessary for adsorption studies? Thanks again. Paolo 2018-07-25 13:21 GMT-04:00 Giovanni Cantele <[email protected]>: > I cannot visualise your structures at the moment, however one first issue, > concerning the adsorption energy calculation is that it seems that in the > system WITOUTH > the molecule you fixed some Ti/O layers, that are instead free to relax in > the adsorbed system. As such, the run with the molecule is able to lower > the total energy > also by allowing those atoms (a lot!), that were fixed in the other run, > to change their positions. The result is that the -0.66 Ry contain also the > energy gain of > the “free” surface when you let those atoms to relax towards a lower > energy configuration. So, one first check would bee to see whether the > atomic positions > of those atoms changed a lot (for example I see the z of one Ti atom equal > to 15.819807000 when it is fixed, and 16.095206282 when it is allowed to > relax, this is a change > of ~0.3 A -> 2% of the initial coordinate, that summed over all those > atoms might make a difference!). > In any case I would try to make a surface (with no molecule) run where all > atoms are allowed to relax and see how much energy is gained with respect > to your run. > > I could give you more hints tomorrow, if I’m able to visualise the > structures > > Giovanni > > -- > > 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: [email protected] <[email protected]> > [email protected] > Phone: +39 081 676910 > Skype contact: giocan74 > Web page: https://sites.google.com/view/giovanni-cantele > > On 25 Jul 2018, at 19:07, Paolo Costa <[email protected]> wrote: > > Dear experts, > > I got nonsense value of adsorption energy by computing 4-iodoanisole on > top of TiO2 anastase surface (101). > By calculating : (Esurface+anisole)-Eanisole-Esurface, I got an > adsoprtion energy of 0.66 ry (8.98 eV), which is too high. > Now I am trying to apply the dipole correction to see if this is the > problem causing an unusual adsorption energy. > > In the following link you can find the output files: > https://www.dropbox.com/sh/edijwg1kyp7gx31/AACD7Up1XIIULbJFToLNqsUra?dl=0 > > I would be glad to receive any suggestions to understand the problem. > > Thanks. > > Paolo > _______________________________________________ > users mailing list > [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users > > > > _______________________________________________ > users mailing list > [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users > -- Paolo Costa, Ph.D. Postdoctoral Researcher Department of Chemistry and Biomolecular Sciences University of Ottawa 10 Marie Curie, Ottawa, ON K1N 6N5, Canada Room number: DRO 326 (D'Iorio Hall)
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