Hi Elaine, I know people in the past have asked a question about the solvent Occupancy Calculation, but please help me. I have an oligosaccharide simulaiton trajectory from AMBER9. I used a 100ps trajectory for solvent occupancy calculation using Chimera. Everything looks absolutely fine. The questions I have are as follows: I have 0-220 in my levels section of volume viewer. If I fix the level of 80, what does that mean? When I'm sliding the bar of levels from left-right what information about solvent density am I obtaining? For example does a value of 80 mean low density when compared with a value of 70? or is it the other way? When I have two different oligosaccharide simulations and I want to say that oligosaccharide 1 has more water density around it, what value of levels should I choose? What I mean by this statement is do I select same value of levels? or do I calculate the percentage i.e., 80/220 for first model gives me 36% and for second sugar if the levels are 0-300 the i should choose a level of 109 which gives 36%? Also is there any reference paper by which Chimera calculates the solvent occupancy? Thanks very much for your time Sai