Automatic guess of initial magnetic_moments

[niklasschmitz]

Currently, to run calculations with collinear spin, the user has to manually provide initial guesses for magnetic_moments. This is used to 1) determine symmetries, 2) set model.spin_polarization to :collinear or :full, and 3) the guess_density for SCF initialization.

Example: https://docs.dftk.org/stable/examples/collinear_magnetism/

It would be nice, if we could instead directly specify a Model to be :collinear (or full?) and have

• an automatic guess for magnetic_moments
• an automatic guess for the initial density

@mfherbst mentioned there is some initial guess magnetic moments in ASE?