I'm very new to Materials Studio and am attempting to get estimates of miscibility for binary mixtures. I've completed the 'calculating the miscibility of 2 polymers' tutorial, but it's not clear how the density should be set when creating the amorphous cell. Is the density used to construct the amorphous cell based on experiments? Is there an acceptable way to estimate the density?

If it helps, I'm trying to run a calculation on a drug molecule and a shorter chain representation of a polymer. 

Thanks!