Generation of Helical States -Breaking of Symmetries, Curie's Principle, and Excited States

Following previous work of M.H. Garner, R. Hoffmann, S. Rettrup and G.C. Solomon, we discuss the generation of helical molecular orbitals (MOs) for linear chains of atoms. We first give a definition of helical MOs and we provide an index measuring how far a given helical states is from a perfect helical distribution. Structural properties of helical distribution for twisted [n]-cumulene and cumulene version of Mobius systems are given. We then give some simple structural assumptions as well as symmetry requirements ensuring the existence of helical MOs. Considering molecules which do not admit helical MOs, we provide a first way to induce helical states by the breaking of symmetries. We also explore an alternative way using excited conformations of given molecules as well as different electronic multiplicities. Several examples are given.