It's called the canonical partition function.
So last time, then, you saw how from the canonical partition function, you could get something like the energy.
Q And now we have our capital Q, our canonical configurational partition function.
In other words, if I have an expression for Q, I know the partition function, and I can calculate it at any temperature.
So now we can just write out the configurational partition function for the molecules and also the canonical partition function for the system.
So we're always writing some molecular partition function.