Yifan Cheng

Electrons — tiny particles in molecules — constantly maneuver, avoiding collisions like passengers during rush hour. To calculate their behavior, scientists set a personal distance rule: a mathematical function that indicates how close one electron can get to its neighbor.

Electrons in a molecule are like dancers trying to keep their distance from each other. But when two get too close, their dance hits a sharp snag — a so-called Coulomb hole (a deep dip in the interaction energy).