The figure (generated by POV-Ray) shows excitations of copper 3d orbitals on the CuO2-plane of a high Tc superconductor; The ground state (blue) is x2-y2 orbitals; the excited orbitals are in green; the arrows illustrate inelastic x-ray spectroscopy; further details: <a rel="nofollow" class="external free" href="http://w3.msi.vxu.se/users/pku/RXR/">http://w3.msi.vxu.se/users/pku/RXR/</a>
<a href="//commons.wikimedia.org/wiki/User:Pieter_Kuiper" title="User:Pieter Kuiper">Pieter Kuiper</a>
<span class="int-own-work" lang="en">Own work</span>