[Pw_forum] Cohesive energy of bulk Iridium

[stefano de gironcoli]

dear Venkataramana Imandi
  nspin=2 + starting_magnetization/=0 should be ok for your case i think.

  the value of the starting magnetization should not be very important. 
Its role is to break the up/down symmetry in the first iteration and 
then the code should reach self consistency.
  Unless the system has many competing solutions with different 
magnetizations the final scf value of the magnetization should be the same.
  The initial value may affect the number of iterations needed to reach 
self-consistency but should not affect the final self consistent 
results. You may want to explore this dependence if you plan to make 
many calculations with different supercells to study defect or other 
properties.
  Starting magnetization can be used to explore different magnetic 
configurations (ferromagnetic, AFM, more complex configurations if many 
inequivalent atoms/sites are present).
In bulk Iridium i think a simple FM solution should be enough.

best

stefano

On 03/10/2015 11:29, Venkataramana Imandi wrote:
> Dear prof. *STEFANO DE GIRONCOLI*
>
> Many thanks for spontaneous reply. On the basis of your answer, If I 
> understood correctly, I can use nspin=2 for atomic Iridium and bulk 
> Iridium
> (since Iridium is paramagnetic from literature data). However, I have 
> to specify starting_magnetization in the input file in the both atomic 
> Iridium and bulk Iridium
> input files. The keywords list information says that values range 
> between -1 (all spins down for the valence electrons of atom type 'i') 
> to 1 (all spins up). Iridium has three unpaired electrons in the spin up.
> 1. It indicates can I use starting_magnetization(1)=1 along with nspin=2.
> 2. If not that value, what value I have to use, I don't know, please 
> suggest me.
> 3. I am not using full relativistic pseudopotential for Iridium, so, I 
> can skip nspin=4, am I correct ?.
>
>  Please verify my assumptions.
>  The reply of previous thread of clean stop of running job, now I got 
> clean stop during running job.
>
> On Sat, Oct 3, 2015 at 12:52 PM, Venkataramana Imandi 
> <venkataramana.imandi at gmail.com 
> <mailto:venkataramana.imandi at gmail.com>> wrote:
>
>
>     Dear all
>
>     I want to calculate ground state total energy of single Iridium
>     neutral gaseous atom.
>     The electronic configuration of Iridium atom is
>     [Xe].4f^14.5d^7.6s^2 and in the 5d orbital, three unpaired
>     electrons are there.
>     So, the resultant spin multiplicity is 4. Hence, in keywords list,
>     nspin=4 or noncolin=.true. is essential.
>     I am asking that whether nspin means spin multiplicity or not ?.
>     Am i correct for determining total energy of Iridium with nspin=4
>     or noncolin=.true. ?
>     In case of bulk Iridium (total atoms=72), then can I skip nspin=4
>     or noncolin=.true. ?
>     In case of bulk Iridium electrons can get paired or not ?
>
>     Finally I want to calculate cohesive energy of bulk Iridium.
>
>     I am extremely say sorry, if questions are fundamental and trivial.
>
>     Any suggestions are appreciated and thanks in anticipated.
>
>
>     venkataramana
>     PhD student
>     IIT Bombay
>     Mumbai
>
>
>
>
> -- 
> venkataramana
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20151003/fd9118ac/attachment.html>