Electron Circulation in a Magnetic Field
Click the orbital image repeatedly to see the rotation.
The changes in sign that occur under rotation around the z-axis.
If there is a low-lying orbital of the correct symmetry, the applied field may induce the circulation of the electrons in a complex and hence generate orbital angular momentum. This diagram shows the way in which circulation may arise when the field is applied perpendicular to the xy-plane (perpendicular to this page).
Rotation about the z axis results in the dx2-y2 moving into the dxy and then into the dx2-y2 and then into the dxy and so on.