Hi,

I have constructed a polyimide structure. After long equilibration procedure with different ensembles, ı run 2 ns NPT at 308K nad 298K. The average density of the unit cells are 1.273 g/cc at 298K and 1.280 g/cc at 308K. I assumed to be the opposite.  I think that it should be more dense at small temperatures, but it does not. And also there should be large difference than 0.007 g/cc between 298K and 308K. I totaly confused, I made a mistake in somewhere, but I could not find it. I attached my structure, if you can help me , I will be very pleased. Thanks a lot.