I thought I could simply Google this question and get a straight, simple answer. Everything but.
Is it simply that the mean velocities of the molecules are increased (so molecular kinetic energy) as pressure increases?
Or is energy going anywhere else internally? I'm discounting possible heat transfer across the considered control volume.
Does some of that energy flow into the molecular structure?
The VanderWalls model is nonlinear, manifesting either attractive or repulsive forces depending on molecular separation. I'm having trouble fitting this model into how energy is stored.
What are the fundamental mechanisms and how does VanderWall fit into the mechanism?