[QE-users] Non-collinear magnetism+spin-orbit coupling scf convergence

[Zeeshan Ahmad]

Hi all,

I am trying to perform a non-collinear magnetic + spin orbit coupling calculation of an odd no of electron system obtained by adding a neutral iodine interstitial in methyl ammonium lead iodide. The SCF cycle converges readily in abinit and VASP but not in quantum espresso. Examples of input and output files used for abinit, qe and VASP are at this link: https://gitlab.com/ahzeeshan/qe-issues/-/tree/master/mag-soc-conv

The system converges in qe when either non-collinear magnetization or spin-orbit coupling are used alone in the input file but not both. It also converges when I specify input_dft=‘pz’. I am using pseudo dojo NC pseudopotentials. A non-collinear PBE calculation without spin-orbit coupling showed that the magnetic state is slightly lower in energy than the non-magnetic state for this system (qe-noSOC folder). 

I have tried using initial density and wavefunctions from non-collinear calculation without SOC or from converged non-collinear calculation with SOC (obtained using input_dft = ‘pz'), changing the eigensolver, mixing, starting magnetization, adding gaussian smearing among others. Any suggestions for obtaining the convergence will be appreciated.


Thanks,
Zeeshan

--
Zeeshan Ahmad
Postdoctoral Scholar
Pritzker School of Molecular Engineering
The University of Chicago
Web: https://ahzeeshan.github.io <https://ahzeeshan.github.io/>
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