One example is the highly symmetric cubane where the cubic symmetry can be imposed as in the example Z-matrix depicted in Table . By optimizing for r CC , r CH , and α the problem size is reduced to three degrees of freedom and cubic symmetry is automatically preserved. The electronic structure calculations were Hartree Fock in a STO-3G basis set and were performed with OpenMolcas. The analytic gradients in cartesian coordinates were transformed using equation 20. The L-BFGS algorithm and its implementation from SciPy was used to guess the structure for the next iteration. The geometry was considered to be converged, if the maximum norm of the gradient was less than 5 • 10 -4 E h and the absolute change of energy was less than 1 • 10 -6 E h . With starting values of r CC = 1.4 Å, r CH = 1 Å, and α = 120°the optimisation of cubane converged after 9 iterations to r CC = 1.561 69 Å, r CH = 1.086 39 Å, and α = 125.27°.