I have carried out some dft simulations as attached file. Dr. Sunil Kumar Ph.D (Chemical Engg. IIT Delhi) M.Tech (Chemical Engg. IIT Delhi) B.Tech (Chemical Engg. IET-CSJMU Kanpur) Scientist-C and Assistant Professor CSIR-National Metallurgical Laboratory Jamshedpur-831007 http://www.nmlindia.org/ https://scholar.google.co.in/citations?user=OchYqugAAAAJ&hl=en&oi=sra
On Thu, Nov 12, 2020 at 10:10 PM Dr. SUNIL KUMAR <[email protected]> wrote: > Thankyou for your explanation regarding Dangling bond. > I have one more question. Is it sufficient to remove one atom Cd (or S) > form CdS crystal or also i need to modify/regenerate pseudo-potential file > to calculate properties related to Dangling bond during DFT simulation? > thanks > Dr. Sunil Kumar > Ph.D (Chemical Engg. IIT Delhi) > M.Tech (Chemical Engg. IIT Delhi) > B.Tech (Chemical Engg. IET-CSJMU Kanpur) > Scientist-C and Assistant Professor > CSIR-National Metallurgical Laboratory Jamshedpur-831007 > http://www.nmlindia.org/ > https://scholar.google.co.in/citations?user=OchYqugAAAAJ&hl=en&oi=sra > > > > On Thu, Nov 12, 2020 at 8:53 PM Giuseppe Mattioli < > [email protected]> wrote: > >> >> Dear Tamas and Kumar >> only to add a few words to the (very pertinent) Tamas' reply: >> 1) Semiconductor surfaces can undergoes very complex reconstruction >> patterns (the 7x7 Si(111) reconstruction being likely the most famous >> case). You will not find complex reconstructions by simply cutting and >> relaxing the slabs, and it is best to search in experimental >> literature, in order not to waste time simulating unphysical systems >> which are never going to converge. >> >> 2) Dangling bonds can be also created inside crystals (e.g, by atomic >> vacancies). It is not clear what kind of dangling bond you are >> referring to. >> >> 3) There is an additional problem when you want to simulate some >> process happening on the surface (e.g., adsorptions of molecules). >> Various strategies can be used, including the saturation of dangling >> bonds on one side of the slab by "pseudohydrogen atoms" having >> fractional charge mimicking that of the pristine bond broken by >> cleavage. >> >> This said, you should "make an educated guess" [cit. John Malkovich >> :-)] and ask less general questions which may (or may not) generate >> more useful answers. >> >> HTH >> Giuseppe >> >> Quoting Tamas Karpati <[email protected]>: >> >> > Dear Dr. Kumar, >> > >> > I guess dangling bonds are written about in DFT textbooks of the >> > physicists' style >> > (in quantum chemistry, ie. clusters rather than crystals, it is less >> > of a problem). >> > >> > The typical problem is that you cut chemical bonds when cleave the >> > crystal (to get a slab). >> > In case of bonds originally dominated by ionic (Coulomb) forces you >> > may still have a closed >> > shell system (ie. just paired electrons) after the cleavage. As for >> > the more covalent >> > bonds, radicals are generated and such high multiplicity electronic >> > states (large >> > magnetizations in terms of QE/PW.x inputs) reorganize to the more >> > stable closed >> > shell systems by changing geometry (you need to reoptimize their >> > geometry) and >> > simultaneously forming new bonds. This way every few surface atom >> > pairs get closer >> > and such bonds form, ie. bonds that were dangling after you made the >> > cut are now >> > in covalent bonds again (no dangling anymore). >> > This you can model by reoptimizing with low (not sure but probably >> > zero) magnetization. >> > >> > CdS has strong bonds carrying both ionic (maybe less) and covalent >> nature >> > (more of the latter). Depending on the cleaving plane you applied to >> > the crystal, >> > you have a high chance to see new Cd-S bonds form. Less probable is >> > that you'll >> > have Cd-Cd bonds or -S-S- bridges but these are also possible if your >> surface >> > atoms are situated so. >> > >> > Another way of treating such systems is to keep the structure as you >> have cut >> > from the crystal and apply a high starting_magnetization in a PW/relax >> job. >> > >> > Be careful, though, as the chemistries you describe by the above two >> methods >> > (reorganization vs. high magnetization) are living in two distant >> Universes. >> > >> > I hope this helps, >> > Tamas >> > >> > On Thu, Nov 12, 2020 at 8:13 AM Dr. SUNIL KUMAR >> > <[email protected]> wrote: >> >> >> >> Dear QE developers and Users. >> >> I am struggling to carry out a DFT simulation of CdS with dangling >> >> bonds using Quantum Espresso DFT packages. I am unable to >> >> understand the phenomena of Dangling bond and its implementation in >> >> QE DFT simulation. I would like to request to you all, kindly >> >> suggest me some tutorial and sample QE scripts for CdS with >> >> Dangling bonds. I will be grateful to you. >> >> >> >> Thanks >> >> With regards >> >> SUNIL >> >> Dr. Sunil Kumar >> >> Ph.D (Chemical Engg. IIT Delhi) >> >> M.Tech (Chemical Engg. IIT Delhi) >> >> B.Tech (Chemical Engg. IET-CSJMU Kanpur) >> >> Scientist-C and Assistant Professor >> >> CSIR-National Metallurgical Laboratory Jamshedpur-831007 >> >> http://www.nmlindia.org/ >> >> https://scholar.google.co.in/citations?user=OchYqugAAAAJ&hl=en&oi=sra >> >> >> >> _______________________________________________ >> >> Quantum ESPRESSO is supported by MaX (www.max-centre.eu) >> >> users mailing list [email protected] >> >> https://lists.quantum-espresso.org/mailman/listinfo/users >> > _______________________________________________ >> > Quantum ESPRESSO is supported by MaX (www.max-centre.eu) >> > users mailing list [email protected] >> > https://lists.quantum-espresso.org/mailman/listinfo/users >> >> >> >> 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: <[email protected]> >> >> _______________________________________________ >> Quantum ESPRESSO is supported by MaX (www.max-centre.eu) >> users mailing list [email protected] >> https://lists.quantum-espresso.org/mailman/listinfo/users >> >
1_CdS_1x1.vc_relax.in
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4_CdS_1X1.bands.in
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2_CdS_1X1.scf.in
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