Assorted Notes and Frequently Asked Questions

Occasionally the final energy obtained is different, or the pattern is slightly varied. Why?

The simulated annealing process used by SimSurface is inherently random in nature. Thus when run with different random seeds, the program may produce different output patterns. However the differences in energies should be very small.

SimSurface is great, but I'm looking for an example of simulated annealing that does not require as much understanding of physics. Any suggestions?

Why yes. We also have a program titled SimElevator which uses the same annealing process to model the way in which people arrange themselves in an elevator. If there's sufficient interest in this (mail us), we would consider creating a Mosaic front end to this as well.

Is source code for SimSurface publicly available?

In a word, no. But now you can build, run, and observe your surface model as a JAVA application run locally from user's hard disk by accessing the beta version of the MASTER SimSurface simulation software.

What's the coolest thing about SimSurface?

Our opinion: when we find the minimum energy configuration of 64 electrons, we are in essence solving a global minimum problem in 128 dimensions. If instead we just tested each coordinate at each of 10 values (a very coarse sampling), we would have 1.0e128 energy calculations. Needless to say this would take longer than the age of the universe. Instead, our program runs in about 6 seconds. Thus as you can see the algorithm used is far more important than whether the program is run on a Cray, an SGI or a Macintosh.