The electronic structure of the molecule is represented using density functional theory, as described in [1]. You can attempt to minimize the energy by varying the shielding parameters , and the bond distance . The results will, of necessity, be approximate, owing to the limitation in the density function . Computed Hartree–Fock energies and experimental bond distance are shown for comparison. Minimization with respect to is especially delicate, so do not expect an accurate result for the bond distance.