Interplay between magic number stabilities and superfluidity of small parahydrogen clusters

Area of Science:

• Quantum many-body physics
• Low-temperature condensed matter physics
• Atomic and molecular clusters

Background:

• Parahydrogen (H2) clusters are model systems for studying quantum phenomena.
• Magic numbers in clusters indicate enhanced stability due to specific shell fillings.
• Superfluidity is a quantum mechanical phenomenon characterized by dissipationless flow.

Purpose of the Study:

• To investigate the relationship between magic number stabilities and superfluidity in parahydrogen clusters.
• To explore the impact of cluster size (N=5-40) and temperature (0.5-4.5 K) on superfluid properties.
• To understand the microscopic mechanisms governing superfluidity in these systems.

Main Methods:

• Classical and quantum path integral Monte Carlo simulations were employed.
• Superfluid fractions were calculated for various cluster sizes and temperatures.
• Analysis focused on the role of magic numbers and molecular exchange cycles.

Main Results:

• Clusters with N<26 and T
• Superfluidity was suppressed in larger clusters, particularly at magic numbers (26, 29, 32, 37).
• Below 1 K, superfluidity was regained for specific cluster pairs (27,28; 30,31; 35,36).

Conclusions:

• Magic number stabilities and temperature critically influence superfluidity in parahydrogen clusters.
• Superfluidity is primarily a surface phenomenon, linked to extended exchange cycles of loosely bound molecules.
• The findings provide insights into the quantum behavior of finite bosonic systems.