Quantum Features of a Barely Bound Molecular Dopant: Cs2(3危u) in Bosonic Helium Droplets of Variable Size

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• 作者：Ricardo Pe虂rez de Tudela ; David Lo虂pez-Dura虂n ; Toma虂s Gonza虂lez-Lezana ; Gerardo Delgado-Barrio ; Pablo Villarreal ; Franco A. Gianturco ; Ersin Yurtsever
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：June 30, 2011
• 年：2011
• 卷：115
• 期：25
• 页码：6892-6902
• 全文大小：1066K
• 年卷期：v.115,no.25(June 30, 2011)
• ISSN：1520-5215

文摘

We present in this work the study of small ⁴He_N鈥揅s₂(³危_u) aggregates (2 鈮?N 鈮?30) through combined variational, diffusion Monte Carlo (DMC), and path integral Monte Carlo (PIMC) calculations. The full surface is modeled as an addition of He鈥揅s₂ interactions and He鈥揌e potentials. Given the negligible strength and large range of the He鈥揅s₂ interaction as compared with the one for He鈥揌e, a propensity of the helium atoms to pack themselves together, leaving outside the molecular dopant is to be expected. DMC calculations determine the onset of helium gathering at N = 3. To analyze energetic and structural properties as a function of N, PIMC calculations with no bosonic exchange, i.e., Boltzmann statistics, at low temperatures are carried out. At T = 0.1 K, although acceptable one-particle He鈥揅s₂ distributions are obtained, two-particle He鈥揌e distributions are not well described, indicating that the proper symmetry should be taken into account. PIMC distributions at T = 1 K already compare well with DMC ones and show minor exchange effects, although binding energies are still far from having converged in terms of the number of quantum beads. As N increases, the He鈥揌e PIMC pair correlation function shows a clear tendency to coincide with the experimental boson-liquid helium one at that temperature. It supports the picture of a helium droplet which carries the molecular impurity on its surface, as found earlier for other triplet dimers.