# Origin in Inertial Frame for Spin-Orbit Coupling?

1. Jan 26, 2012

### nonequilibrium

Hello,

I've seen spin orbit coupling being explained by going to the rest frame of the electron and noting that the proton is then a moving charge and hence has a magnetic field, which interacts with the spin of the electron, effectively coupling the spin and angular momentum of the electron.

What is the physical origin as seen from the inertial reference frame? If I would have to take a guess: the electron has an intrinsic magnetic field, and if it is orbiting, this magnetic field is changing in time, and hence induces an electric field, which interacts with the proton, so this changes the Hamiltonian with a term that should depend on L and S (of the electron).