An examination of a b i n i t i o results for the helium potential energy curve

Abstract

A b i n i t i o calculations of transition probabilities and potential curves of SiH A b i n i t i o correlated potential energy surfaces for monomeric sodium and potassium cyanides A b i n i t i o SCF calculations on the potential energy surface of potassium cyanide (KCN)Obtaining a ground state potential energy curve for helium has been the subject of much research involving empirical, semiempirical, and ab initio methods. In this work, we examine critically recent ab initio potentials proposed for this interaction with respect to their ability to predict certain accurate experimental data. To accomplish this analysis, potentials with a modified HFD-B form were fit to the recent theoretical work of van Duijneveldt and coworkers [Vos, van Lenthe, and van Duijneveldt, J. Chem. Phys. 93, 643 (1990) and Vos, van Mourik, van Lenthe, and van Duijneveldt (to be published)] and Liu and McLean [J. Chem. Phys. 91, 2348(1989]. A well depth (Elk = 10.92 K) and a separation at the minimum (r m = 2.9702 A) consistent with both determinations were chosen and the properties of helium were calculated based on these potentials. These "mimic" potentials fail to predict the very low temperature 4He and 3He virials and one ofthem [Vos, van Maurik, van Lenthe, and van Duijneveldt (to be published)] also fails to predict the very accurate room temperature viscosity of Vogel [Ber. Bunsenges. Phys. Chern. 88, 997 (1984)]. For a potential which was fit as closely as possible to the LM-2 potential at its maximum suggested depth (dk = 10.97 K), the virials are satisfactorily predicted. This compromise potential appears to be the best characterization of the He-He interaction in its ability to predict a variety of experimental data as well as being consistent with ab initio results.

Calculations of the binding energies of weakly bound He-He-H, He-He-H-and He-H-H molecules

“…The latter is expected to be small and in the case of the He-He-He system it has been shown to contribute to less than 1% to the ground state energy [25,26]. For the He-He pair interaction, we used the one from Aziz and Slaman [27]. Other newer potentials have been proposed recently [29,30], but they do not differ much from the one employed here.…”

Approaching Universality in Weakly Bound Three-Body Systems

“…As pointed out by Efimov and Tkachenko [5], for a , LM2M2 [7], HFD-B [8] and HFDBFCI1 [9]. Note the approximately linear relationship (dashed line).…”

Weakly bound states with spin-isospin symmetry

“…The second correction is the introduction of a finite-range parameter, Γ 3 n , depending on the energy level, which produces a shift in the product κ * a B . Recently it has been shown that the value of the shift is almost the same for very different potentials in range and scale as the LM2M2 interaction of Aziz [8], a gaussian potential reproducing the values of E 2 and a given by that interaction and a combination of yukawians, the MT-III interaction [9], describing the s-wave triplet n − p state. Interestingly the value of the shift for the ground state in the three cases results to be almost the same, Γ 3 0 ≈ 0.8 [10].…”