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

We report results for the ground-state energy and structural properties of small (4)He-T down arrow clusters consisting of up to four T down arrow and eight (4)He atoms. These results have been obtained using very well-known (4)He-(4)He and T down arrow-T down arrow interaction potentials and several models for the (4)He-T down arrow 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 down arrow interatomic potential but the stability limits remain unchanged. The only exception is the (4)He(2)T down arrow trimer whose stability in the case of the weakest (4)He-T down arrow interaction potential is uncertain while it seems stable for other potentials. The mixed trimer (4)He(T down arrow)(2), a candidate for the Borromean state, is not bound. All other studied clusters are stable. Some of the weakest bound clusters can be classified as quantum halo as a consequence of having high probability of being in a classically forbidden region.

long-range interactions ; H-He ; energy-levels ; hydrogen ; system ; atoms ; gas ; scattering ; impurity ; trimer

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