This paper investigates the Jahn–Teller effect in the icosahedral cation B₈₀⁺ and compares the descent in symmetry with that in C₆₀⁺. For both cations the icosahedral ground state is a ²Hu state, which exhibits a H ⊗ (g ⊕ 2h) Jahn–Teller instability. A detailed construction of the potential energy surface of B₈₀⁺ using different DFT methods including...