Rotational Hamiltonian for space-quantised electron spin

Rotational Hamiltonian for space-quantised electron spin 

This is, of course, similar to (2.120) for molecule-quantised electron spin the expansion of 3Cei will, however, be somewhat different, as we shall see. 

We could return to the exact equation (2.131) and examine the matrix elements of the Cn, n terms in the same manner as we dealt with the diagonal Cn n terms. It is, however, easier to turn to the form of the exact Hamiltonian given in equations (2.113) and (2.120). The terms in this Hamiltonian which cause a breakdown of the adiabatic separation of nuclear and electronic motion are 

This term has matrix elements off-diagonal in f2, i.e. between different electronic states. 

We shall show in chapter 7 that these matrix elements are of the form 

---

Rotational Hamiltonian for space-quantised electron spin [1 67... 

---