Extended Data Fig. 3: Depiction of two-centre two-electron σ(Cm–S) NLMOs.

a, NLMOs (isosurface of ±0.02) obtained from the MC-pDFT+SO/tPBE wavefunctions of the lowest-energy components of the ⁸S_7/2 ground state and the photoluminescent ⁶D_7/2 state of Cm-1 at 0 GPa (left) and 11 GPa (right). NLMO compositions (averaged over the eight Cm–S bonds), aggregate Cm Wiberg bond index (WBI) and NLMO/NPA-based effective bond order (EBO^NLMO/NPA, obtained from the NLMO shared occupancies and bonding–antibonding overlap) (NPA, natural population analysis). b, NLMOs, aggregate Cm WBI and EBO^NLMO/NPA of the ⁸S_7/2 ground state of Cm-2 (theoretical model).