On 07/25/2010 07:29 AM, Weyl Fang wrote: > Dear all, > > Recently i want to do a spin polarization calculation.
For a metal or an insulator? > After I read the > pw.x input file description, i know if i set the tot_magnetization to > unspecified the amount of electronic magnetization is determined during > the self-consistent cycle. So i set the tot_magnetization to > unspecified. But when i execute pw.x, i get a error message some > starting_magnetization MUST be set. But i get the message" If you fix > the magnetization with "tot_magnetization", you should not specify > starting_magnetization." So, do you really want to fix the total magnetization of the system or do you want it to reach its ground state magnetization? > from the pw.x input file description. If i > still should specify the starting_magnetization? If you are using the broadening of the occupations, I think you should. If you want to fix the total magnetization in this case you should use constrained_magnetization, not tot_magnetization method (which still might work, but probably will not be able to reach self-consistency). > And If i want the > amount of electronic magnetization determined during the self-consistent > cycle, how should i specify the starting_magnetization? > It dipends on your system. In many cases any reasonable value between -1 and 1 is good. If you can guess a value close to that of the ground state then the code will reach self-consistency faster. In complicated systems you may get stuck in some local minimum if the starting_magnetization is too "wrong". HTH GS > Thanks for your help! > > Weyl > > =========================================================================== > > Weyl FANG > Graduate student in Chemical Engineering > State Key Laboratory of Materials-oriented Chemical Engineering > College of Chemistry and Chemical Engineering > Nanjing University of Technology, 210009, Nanjing, Jiangsu, China > **************************************************************************************************************** > Email: weylfang at gmail.com > Office: Room A705, Technical Innovation Building, Xinmofan Road 5#, Nanjing, > Jiangsu, China > ********************************************************************* > ******************************************* > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- Gabriele Sclauzero, EPFL SB ITP CSEA PH H2 462, Station 3, CH-1015 Lausanne
