Electron-electron interaction Hamiltonian.

F = eeint(SpinSys)
F = eeint(SpinSys,eSpins)

eeint returns the electron-electron interaction part of the spin Hamiltonian of the spin system given in SpinSys, in units of MHz.

If the vector eSpins is specified, only the interactions between the electrons listed in eSpins is computed. For example, if eSpins = [1 3] and the spin system contains 3 electrons, only the interaction between electron 1 and electron 3 is returned.

In the spin system structure, the fields ee and eepa parameterize the electron-electron interaction.

For a two-electron system AB

AB = struct('S',[1/2 1/2],'g',[2 2 2; 2.2 2.2 2.2]);
AB.ee = [-1 -1 2]*40;

the electron-electron interaction Hamiltonian (in MHz) is

eeHam = eeint(AB)

eeHam =
    20     0     0     0
     0   -20   -20     0
     0   -20   -20     0
     0     0     0    20

E = eig(eeInt)

E =
   -40
     0
    20
    20

hfine, internal, nquad, sham, zeeman, zfield