Regensburg 2025 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 36: Nanotubes, BEC, Cryocoolers: Poster
TT 36.4: Poster
Wednesday, March 19, 2025, 15:00–18:00, P3
Quantum Solvation of Flexible Molecules at Low Temperatures from Path Integral Simulations — •Katharina Leitmann1, Harald Forbert1,2, and Dominik Marx1 — 1Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780 Bochum, Germany — 2Center for Solvation Science ZEMOS, Ruhr-Universität Bochum, 44780 Bochum, Germany
Protonated methane (CH5+) is a fluxional molecule whose sensitivity to its environment makes it an excellent probe for studying molecular interactions at low temperatures. We investigated CH5+ microsolvation in para-hydrogen clusters (pH2)n subject to bosonic exchange at 1 K using a hybrid simulation approach that combines Path Integral Molecular Dynamics (PIMD) for CH5+ and bosonic Path Integral Monte Carlo (PIMC) to establish Bose-Einstein statistics of the (pH2)n quantum solvation environment.
Our simulations, based on highly accurate High-dimensional Neural Network Potentials parametrised using coupled cluster theory (CCSD(T)), demonstrate stable solvation of CH5+ at least up to n=12 pH2 molecules, which we found to build the first solvation shell. We revealed, that the structure of CH5+ is not significantly perturbed by the solvation with pH2. But we revealed significant fluctuations in the large amplitude motion of CH5+ associated to the phenomenon of partial hydrogen scrambling as a function of cluster size n. Further, we investigated the superfluid properties of pH2 clusters. Analysing the superfluid fraction and bosonic permutation patterns, indicates the manifestation of superfluidity.
Keywords: Flexible molecules; Superfluidity; Path integral simulations; para-hydrogen; Neural network potentials