where the orbitals ψ elec i are eigenfunctions of ∆P elec (particle NTOs), with eigenvalues λ 2 i , and the functions ψ hole i are eigenfunctions of ∆P hole (hole NTOs), with eigenvalues -λ 2 i . 78 It has been suggested that ∆r correlates with D CT in the NTO basis, 17 although reasonable correlation is also observed using CMOs. For visualization purposes, one typically examines only the occupied/virtual NTO pair having the largest amplitude, namely, ψ hole 1 and ψ elec 1 if we order the eigenvalues as