I would first check if the structure was realy completely solved in previous work. I found that e.g. in the Pearson's crystal data base the structural parameters (atomic positions) for the prototype are reported for many compounds. If one uses these parameters (and they do not accidentially fit the real ones) then the electronic structure will be most probably not correct, this concerns also all other parameters (e.g. magnetic moments, optical spectra, etc.) Indeed you do not need to optimize positions if they are fixed by symmetry.
Therefore my advice is, if the structure was not determined by yourself (or in your group) you should optimize it first before thinking about the calculated properties. In some cases you may find afterwards that the structure initially thought about might be wrong. Ciao Gerhard DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy: "I think the problem, to be quite honest with you, is that you have never actually known what the question is." ==================================== Dr. Gerhard H. Fecher Institut of Inorganic and Analytical Chemistry Johannes Gutenberg - University 55099 Mainz and Max Planck Institute for Chemical Physics of Solids 01187 Dresden ________________________________________ Von: Wien [wien-boun...@zeus.theochem.tuwien.ac.at] im Auftrag von t...@theochem.tuwien.ac.at [t...@theochem.tuwien.ac.at] Gesendet: Montag, 24. Juli 2017 14:47 An: A Mailing list for WIEN2k users Betreff: Re: [Wien] experimental vs relaxed parameters using wien2k Hi, If you are not interested in structural properties because this is not the topic of the paper you want to write, then just use the available experimental structure for band structure, optics, etc. When no experimental structure is available, then you have no choice but the problem is to choose the appropriate functional to calculate the structure. FT On Monday 2017-07-24 14:27, Chouaib AHMANI FERDI wrote: >Date: Mon, 24 Jul 2017 14:27:43 >From: Chouaib AHMANI FERDI <ahmaniferdichou...@gmail.com> >Reply-To: A Mailing list for WIEN2k users <wien@zeus.theochem.tuwien.ac.at> >To: wien@zeus.theochem.tuwien.ac.at >Subject: [Wien] experimental vs relaxed parameters using wien2k > >Greatings Wien users, > >I just want to ask if the experimental parameters (lattice parameters, >internal parameter, atomic positions, ...) are already available for a >certain compound, would it be better to run SCF cycle with them or to make >preliminary relaxation and volume optimization and then perform SCF cycle >using the calculated parameters. > >Faithfully, > > > >-- >AHMANI FERDI Chouaïb >Ph.D Student in Material Science >Ecole Normale Supérieure >Mohammed V University, Rabat. >Tel : +212 6 94 59 57 60 > > >[signature.gif?u=139409&e=8673185&v=632ab2fe5f7587109472ad46fdedd2b235e7342 >ab64c99b4930f7b42d8fd3fb2] > _______________________________________________ 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
