Encapsulation of a Water Molecule inside C60Fullerene: The Impact of Confinement on Quantum Features

10 pags., 5 figs., 2 tabs.We introduce an efficient quantum fully coupled computational scheme within the multiconfiguration time-dependent Hartree (MCTDH) approach to handle the otherwise extremely costly computations of translational-rotational-vibrational states and energies of light-molecule endofullenes. Quantum calculations on energy levels are reported for a water molecule inside Cfullerene by means of such a systematic approach that includes all nine degrees of freedom of HO@Cand does not consider restrictions above them. The potential energy operator is represented as a sum of natural potentials employing then-mode expansion, along with the exact kinetic energy operator, by introducing a set of Radau internal coordinates for the HO molecule. On the basis of the present rigorous computations, various aspects of the quantized intermolecular dynamics upon confinement of HO@Care discussed, such as the rotational energy level splitting and the significant frequency shifts of the encapsulated water molecule vibrations. The impact of water encapsulation on quantum features is explored, and insights into the nature of the underlying forces are provided, highlighting the importance of a reliable first-principles description of the guest-host interactions.The authors thank Centro de Calculo del IFF, SGAI (CSIC), and CESGA for the allocation of computer time, and the CSIC (URICI) open access publication support initiative for the support of the publication fee. The authors acknowledge financial support by MINECO Grant no. FIS2017-83157-P and COST Action CA18212(MD-GAS). This work has been supported by the SEGIB Research Fellowshipthe Carolina Foundation and the Universidad Nacional de Colombia Hermes code: 49572