Because the classical MD simulations address only ground state dynamics, ground state QM suffices to generate reliable fitting targets, including energies and energy gradients with respect to atomic positions. We chose DFTD3/DZVP level of theory, as it has been shown to strike a favorable balance between accuracy and computational cost in calculating conformational energies for molecules of this size . The motor rotation process of interest involves conformations where the central carboncarbon bond is twisted, so that atoms 16-15-14-13 are not coplanar. In such conformations, π orbital overlap is compromised, resulting in open shell character of the electronic structure; this motivated us to use unrestricted DFT orbitals.