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Extremely floppy molecules are indescribable by the common ideas of molecular physics. Their ground state wave functions are highly delocalized and the concept of molecular structure breaks down. Recently, we established a fundamentally new 'super-rotor' model, which is based on a five-dimensional rotational symmetry. The respective states are described by the irreducible representations of SO(5) and the Hamiltonian is proportional to the respective Casimir operator. The prototypical example of floppy molecules is protonated methane, which was measured only recently in the Cologne lab. With our simple model, we are - for the first time - able to predict energy levels which actually compare very favourably to the experimental values. In addition, the exchange symmetry of the protons can be determined by using an isomorphism of the permutation group to a subgroup of SO(5). In this talk, we discuss the basic concepts of this new approach and ask some of the most urgent questions for further developments.

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Hanno Schmiedt, University of Cologne
TP seminar room 0.03
Contact: Alexander Altland