I've yet to clearly understand the difference between these two disciplines, and I was wondering if anyone else had any insights. I first thought they were one and the same, but they are certainly used as different terms in most universities. I've come to understand it as a difference of scales. When one is performing analyses on only a few molecules or atoms, such as electronic or molecular structure calculations and density functional theory calculations, I view that as chemical physics (particularly if quantum mechanics is used). On a more macroscopic scale where one is looking at bulk thermodynamic properties I view that as physical chemistry. Reaction kinetics and statistical thermodynamics are kind of in the middle of these two. That's just my guess though. Any thoughts?
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