Structure and energetics of small helium clusters: Quantum simulations using a recent perturbational pair potential

Abstract

We report accurate ground state energies and structural properties for small clusters of 4He computed with the diffusion quantum Monte Carlo (DMC) method combined with high quality trial wave functions and using the recent analytical pair potential of Tang, Toennies, and Yiu [Phys. Rev. Lett. 74, 1546 (1995)]. Calculations based on the older HFD-B(He) potential are reported for comparison. The clusters are found to be extremely floppy and to be characterized by very diffuse wave functions. The DMC results for 4He2 and 4He3 are in excellent agreement with other calculations using conventional methods. 4He3 is found to have a noticeable contribution from nearly linear geometries. The internal structure of the clusters is described by a three particle correlation function which reveals a significantly non-spherical internal cluster structure. The energies for all cluster sizes are found to be slightly higher than those obtained with the HFD-B(He) pair potential. Exploratory calculations on the helium trimer indicate that the effects of three body interactions do not exceed the uncertainty margin provided by different state of the art pair potentials.

Binding energies and scattering observables in the 4He3 atomic system

“…However, most of the theoretical investigations consist merely in computing the ground-state energy and are based on variational methods [10][11][12][13][14][15], on Hyperspherical Harmonics expansion methods in configuration space [16,17], and on integral equations in momentum space [18,19]. We further note that the results of Ref.…”

Energetics and structural properties of three-dimensional bosonic clusters near threshold

“…For small clusters with about up to N = 10 atoms, each atom has roughly the same average distance to all other atoms in the cluster. In this case, our variational wave function ψ T is written as a product of pair wave functions φ [37],…”

Universality in the three-body problem for4Heatoms

“…However, there have been extensive theoretical calculations of the fewbody problem for 4 He using modern two-body potentials [11,12]. Theoretical calculations of trimer binding energies have also improved, so that they now have several digits of accuracy [13,14,15,16]. They indicate that there are two trimers: a ground state with binding energy B (0) 3 and an excited state with binding energy B (1) 3 .…”