arXiv:physics/0303031 · Physical Review A
Scaling predictions for radii of weakly bound triatomic molecules
Marcelo Takeshi Yamashita, R.S. Marques de Carvalho, Lauro Tomio, T. Frederico
Abstract
The mean-square radii of the molecules ${}^{4}{\mathrm{He}}_{3},$ ${}^{4}{\mathrm{He}}_{2}{\ensuremath{-}}^{6}\mathrm{Li},$ ${}^{4}{\mathrm{He}}_{2}{\ensuremath{-}}^{7}\mathrm{Li},$ and ${}^{4}{\mathrm{He}}_{2}{\ensuremath{-}}^{23}\mathrm{Na}$ are calculated using a three-body model with contact interactions. They are obtained from a universal scaling function calculated within a renormalized scheme for three particles interacting through pairwise Dirac-$\ensuremath{\delta}$ interaction. The root-mean-square distance between two atoms of mass ${m}_{A}$ in a triatomic molecule are estimated to be of the order of $\mathcal{C}\sqrt{{\ensuremath{\Elzxh}}^{2}/[{m}_{A}{(E}_{3}\ensuremath{-}{E}_{2})]},$ where ${E}_{2}$ is the dimer and ${E}_{3}$ is the trimer binding energies, and $\mathcal{C}$ is a constant (varying from $\ensuremath{\sim}0.6$ to $\ensuremath{\sim}1),$ which depends on the ratio between ${E}_{2}$ and ${E}_{3}.$ Considering previous estimates for the trimer energies, we also predict the sizes of rubidium and sodium trimers in atomic traps.