The exception to this is if the subsystems are actually identical particles.
When considering identical particles, this is called cohesive force.
Electrons are identical particles because they cannot be distinguished from each other by their intrinsic physical properties.
I understand that no two identical particles can occupy the same energy state with the same quantum numbers.
Some remanence calculations for randomly oriented, identical particles are shown in Figure 5.
For simplicity, consider a system composed of two identical particles.
In physics, the exchange interaction is a quantum mechanical effect between identical particles.
The effects of identical particles can be dominant at very high densities and low temperatures.
This has important consequences for the discussion of identical particles.
These correlations have quite specific properties for identical particles.