Hi Nancy, This is not a Chimera question (or answer)... my only suggestions are (a) asking authors of papers who did similar calculations, or (b) google or other internet search. For example, by googling "download ice structure" I get several links such as <http://rruff.geo.arizona.edu/AMS/result.php?mineral=Ice> However, I would guess that these are bulk structures rather than surface. You might have to start out with bulk structure and let the simulation rearrange the surface depending on what else is in the simulation (again, NOT with Chimera, as it does not do simulations). Elaine ----- Elaine C. Meng, Ph.D. UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab Department of Pharmaceutical Chemistry University of California, San Francisco On Nov 29, 2011, at 7:51 PM, Nancy wrote:

Hi All,

I would like to perform molecular simulations with an ice crystal surface; does anyone know if such a structure file can be obtained online?

Thanks, Nancy