SUPPLEMENT I: Results Associated with a Perfect Surface The following is a supplement to the article "Predicting Microstructure from Atomistic Rule Set Cellular Automata" by K.J.W. Atkinson et al., which is as part of JOM-e, 51 (8) (1999).
Main Text Supplement II: Distributed Surface Roughness Supplement III: Hexagonal Surface Feature Supplement IV: Canyon Surface Feature

For this work, the starting surface consists of 100 x 100 atoms and is initially free of argon gas. Movies A-D illustrate the evolution of the surface when exposed to 8% argon flux at different temperatures (each movie frame represents 200 time steps). Figures A-D depict surface evolution at various time steps and temperatures.

In experiments using a perfect surface, the surface tends toward a microstructure that is dominated by either all B- or all C-site gas atoms in the simulations carried out at 90 K, 100 K, and 120 K. It seems that the rate at which the microstructure attains its final, essentially single-site state is greater at 120 K than at 90 K, while at 140 K, the surface is highly dynamic and is no longer able to proceed toward a single-site configuration. It is also apparent that at 140 K there is an overall reduction in the surface coverage. The change from stable evolution to a dynamic coverage occurs at a critical temperature.

Color Key
Argon Gas Atom on B Site	Argon Gas Atom on C Site

Movie A (~1.2 Mb) T = 90 K	Figure Aa t = 100; T = 90 K	Figure Ab t = 1,000; T = 90 K	Figure Ac t = 10,000; T = 90 K	Figure Ad t = 100,000; T = 90 K
Movie B (~1.5 Mb) T = 100 K	Figure Ba t = 100; T = 100 K	Figure Bb t = 1,000; T = 100 K	Figure Bc t = 10,000; T = 100 K	Figure Bd t = 100,000; T = 100 K
Movie C (~3 Mb) T = 120 K	Figure Ca t = 100; T = 120 K	Figure Cb t = 1,000; T = 120 K	Figure Cc t = 10,000; T = 120 K	Figure Cd t = 100,000; T = 120 K
Movie D (~4.1 Mb) T = 140 K	Figure Da t = 100; T = 140 K	Figure Db t = 1,000; T = 140 K	Figure Dc t = 10,000; T = 140 K	Figure Dd t = 100,000; T = 140 K