On Fri, 2015-01-02 at 10:05 -0600, Sai Kumar Ramadugu wrote: > Any suggestions for the above post?
http://www.quantum-espresso.org/faq/self-consistency/#6.5 Paolo > > > Thanks for your time! > > > Regards > Sai > > > > > ------------------------------ > Sai Ramadugu > University of Iowa, Iowa City, USA > > On Mon, Dec 29, 2014 at 4:55 PM, Sai Kumar Ramadugu > <[email protected]> wrote: > Dear QE Users, > > > > I'm confused about how the projwfc.x does the projection to > produce PDOS plots. > > I'm running the calculations of bulk magnetite Fe3O4. It has > two ways to set up the > > structure: cubic (ibrav = 1, with 56 atoms) cell and hexagonal > (ibrav = 4, with 42 > > > atoms) cell. I did PDOS calculation for both of them and > checked different d-orbital > > > components (eg: dz2 and dx2-y2, and t2g: dxy, dxz and dyz) for > octahedral Fe. I found > > > the five different d-orbital distributions are very different > for the same type of Fe. > > > The PDOS of different d-orbitals of octahedral Fe in Fe3O4 > cubic cell shows perfect, > > > classical textbook-style octahedral crystal field splitting, > where dz2 and dx2-y2 are > > > degenerate and dxy, dxz and dyz are degenerate. And their > energy levels also match > > > theoretical bonding, nonbonding and antibonding model. > > > However, the PDOS of different d-orbitals of octahedral Fe in > Fe3O4 hexagonal cell > > > is much more complicated than the cubic one. None of the > d-orbitals are degenerate. > > > Although I can tell that their total d-orbital distribution > must be the same with the one > > > we got from the cubic cell, the "dz2, dx2-y2, dxy, dxz and > dyz" here are NOT the "real > > > ones" that we expected to see as those in cubic case. For > example, a peak that is > > > supposed to be only contributed by dz2 or dx2-y2 (eg) orbital, > is a mixture of all the five > > > d-orbitals. So now we can't get the correct d-orbital eg and > t2g occupancies in > > > hexagonal cell. > > > > I'm thinking why different cell type can make such big > difference in PDOS distributions. > > > I guess the "x, y, z" directions defined by projwfc.x in PDOS > projection is "cell vector- > > dependent". In cubic Fe3O4, all the six Fe-O bonds around > octahedral Fe are parallel > > > to one of the a, b and c cell vectors. So the "x, y, z" in > PDOS projection happen to be the > > > same with the "x, y, z" in Fe crystal field splitting. But in > hexagonal Fe3O4, all of the > > > octahedral Fe-O bonds are off the cell vectors. So the default > "x, y, z" in projection are no > > > longer the same as those that we are looking for on octahedral > Fe sites. > > > So now I'm thinking how to change the way the projwfc.x does > the projection. Because > > > Fe3O4 is just a test for us. We are actually focusing on > hematite Fe2O3, which can only > > > be presented by hexagonal (or rhombohedral) cell where all the > Fe-O are off the cell > > > vectors. I found that there is something wrong with the eg and > t2g PDOS but don't know > > > how to correct it. There seems to be a file called > ".../flib/ylmr2.f90". Is this the one > > > controlling projection directions? Or is there any other way > that we can let projwfc.x does > > > the PDOS projection along the directions that we really want? > > > > I am attaching the figures of pdos calculations for cubic > Fe3O4 and hexagonal Fe3O4. > > > Any suggestions are welcome. > > > Thank you, > > > ---------------------------- > > Sai Ramadugu > > University of Iowa > > > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum -- Paolo Giannozzi, Dept. Chemistry&Physics&Environment, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222 _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
