From:
http://eon.chem.washington.edu/whatis.php
"A common problem in theoretical chemistry, condensed matter physics and materials science is the calculation of the time evolution of an atomic scale system where, for example, chemical reactions and/or diffusion occur. Generally the events of interest are quite rare (many orders of magnitude slower than the vibrational movements of the atoms), and therefore direct simulations, tracking every movement of the atoms, would take thousands of years of computer calculations on the fastest present day computer before a single event of interest can be expected to occur, hence the name EON, which is an immeasurable period of time."