[QE-users] How can we decide the spin state of the relaxed structure

[samala nagaprasad reddy]

Hello QE experts,

I am trying spin polarized DFT studies of Co-corrole complex using QE
(using just gamma point and large box size to avoid interactions),  I am
relaxing the structure using  nspin = 2 and  starting_magnetization(6) =
1.0, as initial guess of Co atom. At the end of relaxation I have observed
the below

total magnetization       =     0.31 Bohr mag/cell
absolute magnetization    =     2.77 Bohr mag/cell
and Final energy   =   -1144.9536036757 Ry

When I minimize the structure in singlet and triplet states by fixing the
total magnetization (non spin polarized gives singlet state, and used
tot_magnetization = 2 for triplet). The relaxed energies are
    Final energy   =   -1144.9318071744 Ry  (singlet)
    Final energy   =   -1144.9537812641 Ry  (triplet)

Regarding this I have few queries
1) what is the spin state of the relaxed complex with
starting_magnetization(6) = 1.0 (singlet/triplet or any other)? It seems
the electronic spin state is singlet bec the total magnetization is 0.31
and is close to 0.
2) In the spin restricted calculations, the triplet state is more stable
than the singlet and how can we understand it from the above?
3) which approach is better (whether the guess starting_magnetization or by
fixing the total magnetization)?

Thanks in advance
Naga
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