[Wien] Spin-polarization and spin-orbit coupling

[Luigi Maduro - TNW]

Dear WIEN2k users,

I have three questions concerning the inclusion of spin in a material in WIEN2k.
The three questions concern the two terms where a spin-dependent term appears in the Pauli Hamiltonian for magnetic systems, which are:

Question 1)
In the Pauli Hamiltonian a term appears which is a dot product of the spin-matrices of the system and an effective magnetic field.
The effective magnetic field is a summation of an external magnetic field and an exchange-correlation term. The exchange-correlation term B_xc, is expressed as a derivative of the density w.r.t. the magnetization (in the LDA framework) and that B_xc is parallel to the magnetization density vector. If I understand correctly then the material of interest is magnetic when B_xc is nonzero.
When doing a spin-polarized calculation, what happens then to the external magnetic field term? Is the external magnetic field term set to zero?


Question 2)
The other term in the Pauli Hamiltonian is the spin-orbit coupling (SOC) term, which is proportional to (1/r x dV/dr ) (dV/dr = the derivative of the potential w.r.t. the radial coordinate).
When doing a calculation including SOC the script init_so asks for the magnetization direction (in hkl).
In a non-spin polarized calculation with SOC the magnetization direction has no meaning, is this correct?


Question 3)
If the system of interest is a magnetic system then a spin-polarized calculation with SOC should give me 1) the strength of the magnetization along the chosen magnetization axis, and 2) the spin-up and spin-down density of states (DOS) along the chosen axis. But a spin-polarized calculation without SOC will not give me the spin-up and spin-down DOS. Is this correct?


Cheers,
Luigi Maduro
PhD candidate
Kavli Institute of Nanoscience
Department of Quantum Nanoscience
Faculty of Applied Sciences
Delft University of Technology

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