Dear Matteo thanks for your quick reply, so another question as i mentioned in the former email. if we have different atoms with different number, how we set the value of the keyword below >> ntyp = 1 # number of types of atoms >> na(1) = 2 # number of atoms per type or is it only relate to the atom with a nonzero U value.
best regards! du ?2010-04-05 21:48:59?"Matteo Cococcioni" <matteo at umn.edu> ??? > >Dear Du, > >the input you found below is to extract the U values from a series of >scf calculations. >You can give a look (besides the reference cited below) to the tutorials >you find in this webpage: >http://www.quantum-espresso.org/wiki/index.php/QESB09. >Unfrtunately the value of U is generally not portable and changes >depending on the invironment of the atom in the >specific crystal you are considering. the one you cite is a good >example: Fe in bulk Fe and in FeO. >So in principles we need to recompute it each time. > >hope this helps. > >Matteo > > >duchl06 wrote: >> dear pw users >> i want to do a calculation of V chain absorb on a plane with DFT+U, >> but i donot know how to determine the value of U. >> i found a PPT on the pwscf's media site, they said the value of U >> could be decised by a linear response approach. >> but i really donot understand that like the input file resp_mat.in >> >> &input_mat >> ntyp = 1 # number of types of atoms >> na(1) = 2 # number of atoms per type >> if we have different type atoms with different number, how we set these? >> >> nalfa = 5 # number of perturbations (alpha) >> filepos = 'pos_sc1' # file containing the atomic positions and the >> vectors of the unit cell >> back = 'neutral' # to add a neutralizing ?background?. see PRB 71 >> 35105 (2005) >> what does this mean >> filednda = 'file_sc1' # file containing the names of the files dn*dat >> n1 = 4 >> n2 = 4 # number of unit cells in each direction to construct the >> supercell for >> n3 = 4 # extrapolation (in this case a 4x4x4 supercell of the SC one) >> &end >> >> and they get the U is about 2.4ev for the iron, and they use 4.3ev for >> the FeO calculation, >> we always need a linear response approach to get the U for every system >> or just a U for a certain pseudopotential (i mean if we get a U for V >> bulk, then if i could use this value for another system with V atom, >> like V2O3 etc.) >> any suggestions or comment would be OK. >> thanks >> >> Du >> xiaguanying university >> >> >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100405/53ae7787/attachment.htm
