You may have heard this already: this years Nobel prize in chemistry went to Richard F. Heck, Ei-ichi Negishi, and Akira Suzuki "for palladium-catalyzed cross couplings in organic synthesis". Like last year, molecular modeling and animation is here to bring the science behind the prize to life. This time, through the very excellent Chemtube3D (a Molecular Modeling Basics favorite) and its page on on organopalladium chemistry.
Here is a screencast showing 2 simulations I made to illustrate energy states (often also called microstates). Open any book on statistical mechanics and you'll see a formula like this (for the Boltzmann distribution),
and, perhaps, a figure much like this.
But what are these "energy states" and ε's exactly? Hopefully the screencast and associated simulations, which you can find here and here, will help make this clearer.
About the simulations
If you want to play around with the HCl simulation, note that you have to reload the page if you want to change the translational motion. This simulation is made with Jmol. The molecular dynamics simulation of butane is made with Molecular Workbench.