Dear Ernane, Have you thought of using a more sophisticated method (like GW) on [CO3]- to calculate its EA? This would give you the energy of [CO3]2- in vacuum. Best, Michal Krompiec University of Southampton & Merck KGaA
On Fri, 15 Mar 2019 at 18:22, Ernane de Freitas Martins <ernane...@gmail.com> wrote: > Dear Giuseppe, > > I really appreciate your answer. Thank you very much for using your time > to answer my question. > > I'll think on your suggestion about trying hybrid functionals. The point > is that I need to estimate the solvation energy for carbonate ion using the > environ module, then I'll need to run a vacuum calculation using the same > functional I'm already using rVV-10). > > Thank you again for replying. > > Atenciosamente, > > > Dr. Ernane de Freitas Martins > Postdoctoral researcher > IF - USP > São Paulo, SP - Brazil > > Em sex, 15 de mar de 2019 15:04, Giuseppe Mattioli < > giuseppe.matti...@ism.cnr.it> escreveu: > >> >> Dear Ernane >> Your question contains part of the answer! Carbonate ion (CO3 2-) is >> not stable outside water, and calculations of its properties in gas >> phase are likely not so meaningful, but in the case of model >> thermodynamics cycles (e.g. Born-Haber). The excess negative charge is >> unbound when not stabilized by a strongly polar solvent, and this is >> likely responsible for instabilities in the construction of the >> Kohn-Sham potential along scf iterations. Moreover, this happens on >> top of the strong delocalization error you experience when you use a >> standard GGA exchange-correlation functional, when the >> self-interaction of strongly localized electrons in the J[n] Coulomb >> potential is not cancelled by a same term in the semi local exchange >> potential. You may minimize this latter source of error by using a >> hybrid GGA-EXX functional such as B3LYP, where the non local >> Hartree-Fock part of the exchange functional can recover part of the >> delocalization error, but you are not free yet from the instability of >> carbonate in gas phase. >> HTH >> Giuseppe >> >> Ernane de Freitas Martins <ernane...@gmail.com> ha scritto: >> >> > Hello, >> > >> > I'm experiencing a problem to run a negatively charge molecule in >> quantum >> > espresso. The system is CO32-. >> > >> > I try both vacuum and solvated (environ) calculations. The solvated one >> > works fine. >> > >> > The problem is the calculation in vacuum. It never give the first ionic >> > step because the SCF accuracy never reaches the convence criterion. >> > >> > I tried many different solutions (increase cutoffs and box size, use >> assume >> > isolated, decreasing and changing the mixing scheme and etc) and nothing >> > works. >> > >> > The unique calculation that works fine for vacuum is the one with a box >> > size of 7.9 x 7.9 x 7.9 A. I really don't understand why it only works >> for >> > this specific box size. >> > >> > I ran several other charged systems (+1, +2 and -1 total charge) and >> all of >> > them worked fine. The problem appears for -2 total charge in vacuum. >> > >> > Would some of you kindly help me in this? >> > >> > Cheers, >> > >> > Dr. Ernane de Freitas Martins >> > Postdoctoral researcher >> > IF - USP >> > São Paulo, SP - Brazil >> >> >> >> GIUSEPPE MATTIOLI >> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA >> Via Salaria Km 29,300 - C.P. 10 >> I-00015 - Monterotondo Scalo (RM) >> Mob (*preferred*) +39 373 7305625 >> Tel + 39 06 90672342 - Fax +39 06 90672316 >> E-mail: <giuseppe.matti...@ism.cnr.it> >> >> _______________________________________________ >> users mailing list >> users@lists.quantum-espresso.org >> https://lists.quantum-espresso.org/mailman/listinfo/users > > _______________________________________________ > users mailing list > users@lists.quantum-espresso.org > https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________ users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users