On Mon, 13 Oct 2008, Leonardo Matheus wrote: LM> Hello,
hello leonardo, LM> I'm trying to calculate Hirshfeld charges as a postprocess. To do so, LM> I need to obtain the atomic rho for each atom, in real space. I've LM> seen that "atomic_rho.f90" calculates the total rho as a superposition LM> of the individual atomic ones, obtained from the pseudopotentials. LM> But I couldn't understand how this superposition is done, as the LM> internal loop is based on atomic types, and not on individual atoms. I well, for practical reasons it is more efficient to loop over atom types and atoms per atom type. per atom-type parameters only need to be computed once this way. LM> couldn't also find how the atomic coordinates are used (to "center" LM> the charge on the atomic position), and which variable stores them. I LM> saw that it was all done in reciprocal space, and probably this is LM> where I'm confusing myself. i suggest you first have a look into textbook material explaining the implementation of electronic structure calculation with plane wave pseudopotentials (e.g. the books by jorge kohnoff or richard martin). and then read the marx / hutter review which also gives an overview on how the implementation can be done (on the example of the CPMD code, which is not that different as far as the basic principles are concerned). the CPMD code actually does have an implementation of hirshfeld charges determination, but only for norm-conserving pseudopotentials, IIRC, so you can look up how the implementation principles. for implementing it into QE you'll have to figure out how to handle ultra-soft psps contribution to the atomic density on top of everything else. good luck, axel. LM> Can someone please give me a hand? LM> LM> Thanks, LM> LM> Leonardo Matheus LM> Doctorate student - Physics Institute, University of S?o Paulo, Brazil LM> Nanomol group - http://nanomol.if.usp.br LM> _______________________________________________ LM> Pw_forum mailing list LM> Pw_forum at pwscf.org LM> http://www.democritos.it/mailman/listinfo/pw_forum LM> -- ======================================================================= Axel Kohlmeyer akohlmey at cmm.chem.upenn.edu http://www.cmm.upenn.edu Center for Molecular Modeling -- University of Pennsylvania Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323 tel: 1-215-898-1582, fax: 1-215-573-6233, office-tel: 1-215-898-5425 ======================================================================= If you make something idiot-proof, the universe creates a better idiot.
