Dear Davide, All I wanted to know is the following thing: How does espresso capture the randomness in local moments in paramagnetic phase?
Subhradip > Subhradip Ghosh wrote: >> Dear Davide, >> >> Thanks for the reply. >> I guess I understand that a calculation can be only 'non-spin-pol' or >> 'spin-pol'(not PM,FM,AFM etc.) . But, don't we use phrases like these >> during discussions? Atleast, I have been in discussions where people say >> 'PM calcs or FM calcs' which nobody interprets in the literal sense! > Dear Subhradip, > still I don't understand the difference between a "paramagnetic > calculation" or a "ferromagnetic calculation". Do you mean that in one > case the total spin magnetization is zero and in the other case it > is different from zero? > Take for instance the oxygen molecule. Would you perform a "paramagnetic" > calculation or a "ferromagnetic" one? and for bulk iron instead? > >> Nevertheless, let me be more specific. >> How does espresso simulate a paramagnetic state for a system having >> unpaired spins ( a system which does not have closed shells). > Take again the simplest case of the oxygen molecule. We all now that > the ground state is a triplet (a di-radical). So the calculation will > be spin-polarized: > > occupations = 'fixed' > nspin = 2 > multiplicity = 3 (multiplicity = 2S+1) > > Since there are 12 valence electrons, this will place 7 electrons in > the spin up channel and 5 electrons in the spin down channel. > > Davide > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > ************************************************************************ Dr. Subhradip Ghosh Assistant Professor Department of Physics Indian Institute of Technology Guwahati,Assam-781039 India E-mail:subhra at iitg.ernet.in Phone: +91 361 2582717(O) +91 361 2584717(R) Fax: +91 361 2582749 (Physics) +91 361 2690762 (General) ************************************************************************ ----------------------------------------------------------------------------------- This email was sent from IIT Guwahati Webmail. If you are not the intended recipient, please contact the sender by email and delete all copies; your cooperation in this regard is appreciated. http://www.iitg.ernet.in
