Hello! I'm just beginning some volunteer research work on a project and I've been tasked with finding the partition function of a brain tumor that has magnetic nanoparticles injected into it. CT scans provide concentrations and distributions of the magnetic nanoparticles, but I'm quite lost on how to actually find the partition function! It seems that my course work has only taught me how to find the partition function for simple systems and I don't really know where to start looking for techniques on finding the partition function for complex systems such as this. If anyone has some insight or could lead me to some academic papers I could read to get started that would be great. Thank you so much.