thank you for your answers But for my problem is what I have to say that the material is semimetalic since this result is obtained with GW, GGA+U and mBJ?. Or I have to present all the results even those obtained by HF and I would say that the calculations gave different results pending confirmation of the experiment?
2017-08-07 8:38 GMT+02:00 Víctor Luaña Cabal <vic...@fluor.quimica.uniovi.es >: > On Mon, Aug 07, 2017 at 01:32:04AM +0200, Wien2k User wrote: > > I calculated the gap of a material whose experimental value is unknown. > > > > With GGA+U, mBJ potential and GW, I found that this material is semimetal > > (a slight band overlap) but with HF i found it to be semiconductor of > very > > small gap. > > > > How can I know what is the real nature of the gap of this material? > > > > This calculation is a part of a future paper so I have to put all found > > results (GGA + U, mBJ, GW and HF) in spite of what give deferent nature > or > > I have to adopt that of the HF since it is a more accurate method? > > This is a very good question related to the nature and philosophy of > theoretical calculations. > > Assuming that the role of a theoretical calculation is predicting or > duplicating the experimental results is a dead way when the theory is yet > imprecise or incompletely developed. > > In fact, as theory matures it becomes a part of engineering and it > can be accepted that doing a calculation can sustitute performing an > experiment. When designing a building or a bridge. Nobody would accept > that a good resistence analysis is missed, but that means that materials > resistence is well known in advance. > > Until theory reaches that point of development, the role of a good > calculation is determining how dependent are the obtained properties > to the inner parameters of the calculation. So, in your example, > I would give more value to exploring the effects and meaning of the > different methods. > > Also the examination of families of compounds in looking for the most > promising candidates can be of great help, even in early stages of > a research. > > Hope this helps, > Víctor Luaña > -- > . . "Half of the US people use twitter to form its opinion and half > / `' \ also elect the US president. I only hope they are not the same > /(o)(o)\ half". --From a sentence by Gore Vidal > /`. \/ .'\ > / '`'` \ > | \'`'`/ | > | |'`'`| | > \/`'`'`'\/ > ==(((==)))===================================+=========================== > ! Dr.Víctor Luaña, in silico chemist & prof. ! > ! Departamento de Química Física y Analítica ! > ! Universidad de Oviedo, 33006-Oviedo, Spain ! > ! e-mail: <vic...@fluor.quimica.uniovi.es> ! > ! phone: +34-985-103491 fax: +34-985-103125 ! > +--------------------------------------------+ > GroupPage: <http://azufre.quimica.uniovi.es/> > Articles: <http://scholar.google.com/citations?user=Ibl1BWAAAAAJ&hl=es> > git-hub: <https://github.com/aoterodelaroza> > ORCID: 0000-0003-4585-4627; RID: H-2045-2015 > _______________________________________________ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > SEARCH the MAILING-LIST at: http://www.mail-archive.com/ > wien@zeus.theochem.tuwien.ac.at/index.html >
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