One way to explore a 3D PES is to plot a surface in space that connects all (x,y,z) points with the same value of energy V(x,y,z) - the iso-energy surface. Such a surface surrounds the 3D region allowed, classically, for molecular motion at a given value of energy in the molecule. It is instructive to prepare such surfaces for several values of energy and display them, one after another, in the order of increasing energy. I call this procedure the Energy Scan of the PES (ESPES). Examples, using hyper-spherical coordinates for triatomic molecules, follow.
- ESPES for ozone (Flash) - Download PowerPoint
- ESPES for cyclic-N3 (Flash) - Download PowerPoint
Figure 10: Three lowest adiabatic potential energy surfaces of Na3+ molecule. Only T-shaped configurations are shown in this picture. The avoided crossing seem between the two lowest states in the channel region and the conical intersection between the two upper states in equilateral configuration can be seen.