Ground state of small mixed helium and spin-polarized tritium clusters: a quantum Monte Carlo stud

TL;DR

This study investigates the ground-state properties of small helium-tritium clusters using quantum Monte Carlo methods, revealing stability conditions, potential for quantum halos, and the influence of interatomic potentials.

Contribution

It provides the first detailed quantum Monte Carlo analysis of small mixed helium and spin-polarized tritium clusters, highlighting stability thresholds and the potential for quantum halo states.

Findings

At least three atoms are needed to form a bound mixed cluster.

Binding energies are sensitive to the interatomic potential form.

Some weakly bound clusters exhibit quantum halo characteristics.

Abstract

We report results for the ground-state energy and structural properties of small $^4$He-T$\downarrow$ clusters consisting of up to 4 T$\downarrow$ and 8 $^4$He atoms. These results have been obtained using very well-known $^4$He-$^4$He and T$\downarrow$-T$\downarrow$ interaction potentials and several models for the $^4$He-T$\downarrow$ interatomic potential. All the calculations have been performed with variational and diffusion Monte Carlo methods. It takes at least three atoms to form a mixed bound state. In particular, for small clusters the binding energies are significantly affected by the precise form of the $^4$He-T$\downarrow$ interatomic potential but the stability limits remain unchanged. The only exception is the $^4$He$_2$T$\downarrow$ trimer whose stability in the case of the weakest $^4$He-T$\downarrow$ interaction potential is uncertain, while it seems stable for other potentials. The mixed trimer $^4$He(T$\downarrow$)$_2$, a candidate for Borromean state, is not bound. All other studied clusters are stable. Some of the weakest bound clusters can be classified as quantum halos, as a consequence of having high probability of being in a classically forbidden region.