# Thread: Simple description of how the EON project works

1. ## Simple description of how the EON project works

First, thank you all for the computing time you are putting into the EON project. The amount of computing power available in a distributed environment is truly amazing.

I was recently notified about the Free-DC forum. Looking over the posts, it sounds as if the project description is not clear enough. I want to try to explain what is going on in the project in simple terms.

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The EON project, as the name suggests, is trying to simulate atomistic systems over long time scales.

The time scale problem is a major challenge for atomistic simulations in many field including chemistry, physics, and materials science. Putting the problem simply, atoms are light and they move very quickly. In solids, atoms vibrate about 10^15 times per second. If we used computers to directly calculate the motion of atoms, it would take many thousands of years to simulate how they move over a fraction of a second. Since interesting things happen on timescales of seconds or minutes, we need new methodology to investigate these long (for atoms) time scales.

The time scale problem is different from other projects that can be easily handled with distributed computing. With Seti, for example, there are many independent work units that can be given to different processors. In the EON project, it is long times that needs to be simulated. Because time is cumulative, and what happens at one point in time affects the future, we can't just give a little bit to each processor.

EON uses a less direct approach to determine how atomic systems behave over long times. In the EON project, all processors are working on the same project, simulating the same system, all at the same time. Each work unit is a task to figure out one possible way the system can evolve.

In terms of the physics, the current state of the system (the location of all the atoms) is a basin or valley on a potential energy landscape. A mountain landscape makes a good analogy. The system wants to stay as low on the landscape as possible. But, thermal energy causes the system to move randomly so that every once in a while it moves enough to cross a ridge on the landscape and fall into another valley. For the atomic system, such an event would correspond to one or a set of atoms moving in a crystal or rearranging on a surface. This event can be characterized by a saddle point on the landscape -- the lowest point on a ridge separating two valleys. Mathematically, each processor working on the EON project is finding a saddle point, which corresponds to a possible event available to the system.

The server keeps track of the current state. This is shown graphically at http://eon.chem.washington.edu/current.php Each processor determines a possible way that the system can evolve, and calculates the rate for that process. When the server has enough processes to ensure accurate dynamics (typically after 1 hour) it chooses which process should occur using a random number algorithm called kinetic Monte Carlo. At this point, the system is updated to reflect the occurrence of the chosen process, the simulation clock is advanced by the appropriate amount, and the cycle is repeated.

We have been using this system to simulate the growth of metal films, something that is particularly important for catalysis. Understanding how atoms evolve at these small scales over long times is important, and will become increasingly important for many fields, particularly in nanoscience, chemistry and material science.

2. Thanks, graeme! That helps, I think.

Now if we can just get some more crunchers interested...

Oh, a random period messed up your link. Should be this .

3. thank you

4. ## The url 'period' problem

Umm, maybe edit your post and correct it?
I will take a look at joining too.
Currently a member with DHEP & Boinc.

Edit - Added: I have winXP home, should work...eh?

5. The address has been changed to:

http://eon.cm.utexas.edu/

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