On Fri, 2011-11-04 at 15:16 +0100, hariom jani wrote: > Dear fellow QE users, > > I am currently using fully relativistic pseudo-potentials to compute > certain spin-orbit based properties in solids. > Given a silicon system, there are 4 valence and 4 conduction bands > (each doubly degenerate in the spin components) in total. > > When i perform PWscf calculations, I set 'lspinorb' and 'noncolin' (in > the system namelist) to .true. > > I desire that the 2 degenerate spin states of every band be defined as > uniquely up and down (and not merely their linear combinations). > > 1. To achieve this I am currently using 'starting_spin_angle'=true, > but is the correct command to use? If not, what should be done? > 2. Can this done, in spite of using the 'noncolin' command? >
It cannot be done. When there is spin-orbit, the Hamiltonian does not commute with S_z so you cannot divide the bands into up or down. If there is a strong magnetization (much larger than spin-orbit) than the real bands do not differ too much from up or down bands and it might be convenient to start with wavefunctions that are much closer to spin-up and spin-down states than to spin-angle states. In any case at self-consistency the states are no more completely up or completely down. Andrea > Thanks > Hariom Jani > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum -- Andrea Dal Corso Tel. 0039-040-3787428 SISSA, Via Bonomea 265 Fax. 0039-040-3787249 I-34136 Trieste (Italy) e-mail: dalcorso at sissa.it
