Deterministic dispersion: instead of postulating quantum fluctuations, use the static polarizability α (response of the ground-state charge density to a dipole field) and the ionization potential I of each atom. Compute the C₆ coefficient via the Slater–Kirkwood / London formula:

C₆^{AB} ≈ (3/2) · α_A · α_B · I_A · I_B / (I_A + I_B)

This is the static-polarizability limit of the Casimir–Polder integral C₆ = (3/π) ∫₀^∞ α_A(iω)·α_B(iω) dω. Then the dispersion energy E_disp(R) = −C₆/R⁶ emerges from coupled-oscillator algebra alone — no Born rule, no fluctuations, no full TDSE.

Atomic data (atomic units)

α: experimental polarizabilities · I: ionization energies (Ha)

Atom	α (a.u.)	I (Ha)
H	4.50	0.500
He	1.38	0.904
Li	164.	0.198
Be	37.7	0.342
Ne	2.67	0.793
Na	163.	0.189
Ar	11.1	0.579
Kr	16.8	0.515
Xe	27.3	0.446

Pair selector

Atom A  Atom B

Compute C₆ & plot −C₆/R⁶

Reference C₆ values (a.u.)

Pair	London (this calc)	Reference
H–H	—	6.50
He–He	—	1.46
Ne–Ne	—	6.38
Ar–Ar	—	64.3
Kr–Kr	—	130
Xe–Xe	—	286