Long-range interactions between excited helium and alkali-metal atoms

Abstract

The dispersion coefficients for the long-range interaction of the first four excited states of He, i.e., He(2 1,3 S) and He(2 1,3 P), with the low-lying states of the alkali-metal atoms Li, Na, K, and Rb are calculated by summing over the reduced matrix elements of the multipole transition operators. For the interaction between He and Li the uncertainty of the calculations is 0.1-0.5%. For interactions with other alkali-metal atoms the uncertainty is 1-3% in the coefficient C 5 , 1-5% in the coefficient C 6 , and 1-10% in the coefficients C 8 and C 10. The dispersion coefficients C n for the interaction of He(2 1,3 S) and He(2 1,3 P) with the ground-state alkali-metal atoms and for the interaction of He(2 1,3 S) with the alkali-metal atoms in their first 2 P states are presented in this Brief Report. The coefficients for other pairs of atomic states are listed in the Supplemental Material.

Ultracold mixtures of metastable He and Rb: Scattering lengths fromab initiocalculations and thermalization measurements

“…The Lennard-Jones potential is given by V b (r) = −(C 6 /r 6 ) 1 − b/r 6 , where we can tune the depth of the potential, and therefore a, by parameter b. Note that the less accurate C 6 coefficient of Zhang et al [15] gives the same result than the one obtained in this work, showing that a few percent accuracy is sufficient.…”

“…We therefore have calculated the dipolar-and quadrupole dynamic polarizabilities of He * at imaginary frequencies and integrated , which has an accuracy of 0.56%. Finally we include the C 10 coefficient from Zhang et al [15] to the long-range part of our potential.…”

Ab initiointeraction potentials and scattering lengths for ultracold mixtures of metastable helium and alkali-metal atoms

“…For the C 8 and C 10 coefficients we have used the values calculated by Zhang et al [43] for which the authors estimated an uncertainty of about 1%-10%. However, our study of the He * +Rb system has shown that the error bounds for the C 8 coefficient given by Zhang et al were also far too conservative [18].…”

Long-range interactions of excited He atoms with ground-state noble-gas atoms

“…For He, the energy spectra and reduced matrix elements of the multipole transition operators are the same as those used for calculating the dispersion coefficients for the low-lying states [19][20][21][22][23][24] and the polarizabilities of Rydberg states [25]. The wave functions are expanded in terms of Hylleraas-type basis functions,…”