Nonexistence of the decahedral Si20H20 cage: Levinthal`s paradox revisited

The decahedral cage is the theoretically established ground state of the hydrogen saturated Si 20 H 20 fullerene. However it has never been observed experimentally. Based on an extensive exploration of the potential energy surface and by constructing theoretical reaction pathways from possible initial structures to the ground state of Si 20 H 20 , we show that there is no driving force towards the global minimum. There exists a huge number of intermediate structures that consist mainly of collapsed cages. Visiting all these intermediate states to find the ground state is not possible on experimentally relevant time scales. In this way the ground state becomes kinetically inaccessible. We contrast the features of the potential energy landscape of Si 20 H 20 with that of C 60 which spontaneously forms by condensation.