Related Experiment Video
Updated: Feb 25, 2026

Isotopic Effect in Double Proton Transfer Process of Porphycene Investigated by Enhanced QM/MM Method
Published on: July 19, 2019
Quantum Melting and Isotope Effects from Diffusion Monte Carlo Studies of p-H2 Clusters
Joel D Mallory1, Vladimir A Mandelshtam1
1Department of Chemistry, University of California , Irvine, California 92697, United States.
Abstract:
We present a rigorous characterization of the ground state structures of p-H2 clusters and their isotopologues using diffusion Monte Carlo combined with the inherent structures analysis. For the N = 19 cluster we explore the effect of "quantum melting" by quantifying the contributions of local minima to the ground state as a function of continuously varying particle mass. Doubling the cluster size leads to an enormous increase of its complexity: the ground state of (p-H2)38 is highly delocalized over a large number of minima representing all the funnels of the potential energy surface. The ground state of (o-D2)38 is also delocalized, but over a smaller subset of minima, which exclusively belong to the same disordered motif.
Related Concept Videos
Phase Transitions: Melting and Freezing
Molecular Orbital Theory II
Comparing Intermolecular Forces: Melting Point, Boiling Point, and Miscibility
Temporary attractive forces like dispersion are present in all molecules, whether they are polar or nonpolar. They...
Atomic Nuclei: Nuclear Spin State Population Distribution
Mass Spectrometry: Isotope Effect
Atomic Spectroscopy: Effects of Temperature
At thermal equilibrium, the relative populations of excited and ground state atoms can be estimated using the Maxwell–Boltzmann distribution. For example, an increase in temperature...

