Hi Harjanto, Yes, it is automatically calculated as soon as you show a surface. SAS and SES areas are "attributes" of atoms and residues. After you show a surface, you can see histograms of the values and save them to a file using Render by Attribute (under Tools... Structure Analysis). <http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/render/render.html#...> You can select just the residues with some range of SAS values using Select by Attribute, which is another part of that same tool. <http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/render/render.html#...> Please see this previous post for more details: <http://plato.cgl.ucsf.edu/pipermail/chimera-users/2010-October/005693.html> I hope this helps, 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 Dec 9, 2010, at 11:07 PM, Sumitro Harjanto wrote:

Hi Meng, I would like to find out if I can use Chimera to calculate the solvent accessible surface(SAS) of each residue in a model..? I would like to find out, basically, if I show the surface of the molecule, which are the residues buried (SAS = 0) and which are the ones contributing to the surface contour (SAS > 0). Thanks! =] Cheers, Sumitro