Theoretical Study of Triatomic Systems Involving Helium Atoms

Donald H. Kobe

Виталий Александрович Градусов, Vladimir Roudnev, E. A. Yarevsky +1 more

Abstract Results are presented from calculating the spectra of weakly-bound triatomic molecular systems: the Helium trimer and helium–helium alkali molecules. Calculations are made on the basis of the Faddeev equations in the total orbital momentum representation. The existence of excited states with nonzero total orbital momentum of some molecules is confirmed.

Tamaz Kereselidze

Arnoldas Deltuva

Hiroya Suno, Brett D. Esry

Atom-molecule collisions in helium--helium--alkali-metal triatomic systems at cold energies are studied using the adiabatic hyperspherical representation. We consider the elastic collision processes $^{4}\mathrm{He}X+^{4}\mathrm{He}\phantom{\rule{0.16em}{0ex}}\ensuremath{\rightarrow}^{4}\mathrm{He}X+^{4}\mathrm{He}$ and $^{4}\mathrm{He}_{2}+X\phantom{\rule{0.16em}{0ex}}\ensuremath{\rightarrow}^{4}\mathrm{He}_{2}+X$, as well as the reactive collision processes $^{4}\mathrm{He}X+^{4}\mathrm{He}\phantom{\rule{0.16em}{0ex}}\ensuremath{\rightleftharpoons}^{4}\mathrm{He}_{2}+X$, where $X$ is one of the bosonic alkali-metal atoms: $^{7}\mathrm{Li}$, $^{23}\mathrm{Na}$, $^{39}\mathrm{K}$, $^{85}\mathrm{Rb}$, or $^{133}\mathrm{Cs}$. The elastic and reactive collision cross sections are calculated at nonzero collision energies by including not only zero atom-molecule relative angular momentum, $L=0$, processes but also $L>0$ processes. The total cross section for $^{4}\mathrm{He}X+^{4}\mathrm{He}\phantom{\rule{0.16em}{0ex}}\ensuremath{\rightarrow}^{4}\mathrm{He}X+^{4}\mathrm{He}$ is found to increase with the scattering length between $^{4}\mathrm{He}$ and $X$, while the other collision processes are not found to have any systematic dependence on the alkali-metal species $X$.

Hiroya Suno