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<div class="moz-cite-prefix">dear Ary,<br>
<br>
the starting magnetization option is used to break the up/dw
symmetry in the electronic states at the first scf iteration and
select which magnetic configuration is considered (you can suggest
a ferromagnetic configuration or various type of antiferromagnetic
ones depending on how you define the starting_magnetization
variables).<br>
The code then goes on seeking a self consistent solution without
forcing the value of the total magnetization and occupying each
level according to its position w.r.t. a single Fermi energy. <br>
Usually (there is no guarantee, but it usually happens) the
final magnetic configuration is the same
(ferromagnetic/antiferromagnetic) as the one initially suggested
and, for a given magnetic configuration, the particular values of
the starting_magnetization variables do not affect the final self
consistent result (but may affect how many iterations are
necessary to reach self-consistency). <br>
How many electrons end up to be up or dw is determined by the
self consistent process.<br>
If the system does not want to be magnetic, no matter which
starting_magnetization you chose, the final result would be non
magnetic and Nup=Ndw. <br>
<br>
The total_magnetization option corresponds to a different
situation in which you force the system to have a given total
magnetization (therefore a given number of Nup and Ndw electrons)
<br>
This is imposed by defining two distinct Fermi energies (one for
up and one for dw electrons) and if they end up to be different it
can be interpreted as having put the system in a uniform magnetic
field.<br>
<br>
Another option is to force the atomic magnetizations (defined by
integrals in spheres surrounding the atoms) to have certain
values. Check the constrained_magnetization details.<br>
This does not impose a different value of Nup/Ndw. It produces
only one Fermi energy.<br>
<br>
best,<br>
<br>
stefano<br>
<br>
On 18/09/2015 23:07, Ary Junior wrote:<br>
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cite="mid:CAAf5PVSSUerLjJU9A4UVnA6Ly4ocov+y8PhM5xjTodRKj6MqEQ@mail.gmail.com"
type="cite">
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<div>Please,<br>
<br>
</div>
<div>I'm using the variable starting_magnetization(#) instead
of tot_magnetization in a spin-polarized calculation (nspin
= 2), with smearing and degauss > 0.0 (lgauss is
.true.)... The result is that for some starting
magnetization values, there are more bands occupied with
spin up than spin down, with partial occupations at the top
of the valence band... In that case, I was expecting to see
the values of the variables ef_up and ef_dw in the output,
instead of only the value of the variable ef... <br>
<br>
</div>
<div>My question is: why in the file PW/src/input.f90 the
variable two_fermi_energies is .true. only if
tot_magnetization /= -1._DP? In the calculation described
above, the subroutine weights (PW/src/weights.f90) calls the
subroutine gweights (PW/src/gweights.f90) only once, and the
variable ef is set with the bisection method implemented in
the file PW/src/efermig.f90.... Shouldn't it call gweights
twice for ef_up and ef_dw?<br>
</div>
<div><br>
</div>
Thank you very much!<br>
<br>
</div>
Ary Ferreira<br>
<br>
CNPq postdoctoral fellow<br>
TU München<br clear="all">
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