Electronegativity
r = 0.979Electronegativity — how strongly an atom attracts electrons in a bond — correlates with the coherence parameter at r = 0.979. This is the second-strongest correlation in the chemistry data.
Why This Works
Electronegativity measures the strength of electron-atom coupling. High electronegativity (fluorine: 3.98) means electrons are tightly bound, highly correlated with the nucleus. Low electronegativity (cesium: 0.79) means electrons are loosely held, weakly correlated.
This is a direct expression of Ncorr: how many particles (electrons + nucleus) are moving as a correlated unit determines both the electronegativity and the γ value.
Connection to Sound Velocity
Both sound velocity (r = 0.982) and electronegativity (r = 0.979) correlate with γ for the same reason: they both measure aspects of collective coupling. Sound velocity measures atom-atom coupling; electronegativity measures electron-atom coupling. The coherence function captures the underlying correlation structure that drives both.