Hi,
We do "self-consistent" calculations. This means that in most cases, the
electronic configuration of the atoms does not matter.
Only in some magnetic cases, the results may depend on the starting
configuration, and you may be able to obtain a high-spin and low-spin
solution, depending on the starting density (The same happens with the
magnetic order, i.e. ferro-magnetic vs. different anti-ferromagnetic
ordering).
Thus, all we specify in case.inst is the number of spin-up and spin-dn
electrons, but we do NOT select a particular d-orbital. Remember, lstart
produces anyway only spherical densities.
So for the low-spin state of Co put the same number of up and dn
electrons into case.inst, for the high-spin state, start with a large
atomic moment.
The specific occupation of t2g or eg will come out automatically in the
scf prodedure.
Second question: lstart was a non-spinpolarized code (and the input is
still in a non-spinpolarized way, i.e. it is given in a relativistic
notation, but the spin-occupation is defined without considering the
spin-orbit coupling). Thus you cannot calculate a "proper" spin-state in
lstart (with spin-orbit coupling).
All what lstart gives is a spherical !! spin-density, which gives the
desired spin moment when integrated over space.
This is all we need as an input for the scf cycle.
PS: With PBE+U you can manipulate the density matrix and then force
eventually the occupation of certain d-orbitals. (There should be
previous postings on that).
On 9/28/20 9:47 AM, Yfding wrote:
Dear Wien2k developers，
In Wien2k, case.inst file allows to define the spin-state of certain
atoms, and it consists of the relativistic quantum number. It seems that
relativistic quantum number cannot be directly connected with the
occupation of 3dx2-y2, 3dz2, 3dxy, 3dxz, 3dyz. My question is, how do I
set a specific spin state, like low spin Co3+ ( t2g orbit is filled with
3 spin up electrons and 3 spin dn electrons to make the total spin
equals zero while no electron exist in eg orbit ), by rewriting
case.inst file ?
The second question is about Table 6.6: Relativistic quantum numbers in
user's guide. In the last two columns, max. occupation of s = -1 is 4,
and max. occupation of s = +1 is 6 for l = 2. It seems that max.
occupation for d orbit will lead to total spin equals (-1)*4+1*6=2. Is
it right ?
Any comments would be highly appreciated. Thanks in advance!
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P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at
WWW: http://www.imc.tuwien.ac.at/TC_Blaha
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