Long‐range dispersion interactions involving excited atoms; The H(1s)–H(2s) interaction

Abstract

AbstractsThe dispersion interaction between two nonoverlapping atoms (or molecules) is expressed in terms of single-atom "polarizabilities." T h e formulation is valid even if one atom (or both) is in a n excited state. T o illustrate the procedure, the dispersion interaction between a 1s and a 2s hydrogen atom is computed accurately through order R-l0 ( R = internuclear separation).L'interaction dispersionelle entre deux atomes (ou moltcules) bien stparts s'exprime sous forme de plusieurs (cpolarisabilitts)> d'atomes individuels. La formulation est valable m&me si l'un des atomes (ou les deux) se trouve dans un ttat excitt. Pour illustrer le proctdt, on calcule d'une faGon prkcise l'interaction dispersionelle entre un atome d'hydrogkne dans l'ttat 1s et un autre dans 1'6tat Zs, jusqu'aux termes d'ordre ( R = distance internucltaire) .Die Dispersionswechselwirkung zweier nicht uberlappender Atome (oder Molekule) wird in "Polarisierbarkeiten" der Einzelatome ausgedruckt. Die Darstellung gilt auch, wenn ein Atom (oder beide) sich in einem angeregten Zustand befindet. Als Beispiel fur das Verfahren wird die Dispersionswechselwirkung zwischen einem 1s und einem 2s Wasserstoffatom einschliefilich der Glieder in R-l0 genau berechnet ( R = Kernabstand).

Long-range interactions of hydrogen atoms in excited states. III. nS−1S interactions for n≥3

“…[17]) cannot be used with good effect for highly excited states, because of numerical problems associated with the modeling of wave functions with many nodes. These numerical difficulties may be one reason why early numerical calculations for C 6 (2S; 1S) coefficients [5,6] were never generalized to higher excited S states. Eventually, for 4 ≤ n ≤ 12, the D 6 and M 6 coefficients are given in Tables I and II as the generalizations of Eqs.…”

“…We have recently analyzed [1] the interaction of metastable 2S hydrogen atoms with ground-state atoms. A long-standing discrepancy regarding the numerical value of the van der Waals C 6 coefficient could be resolved, and the mixing term was treated for 2S-1S interactions [1,[5][6][7]. In [8], we have analyzed 2S-2S interactions, and we have determined the hyperfine-resolved eigenstates of the van der Waals interaction, both among the S-S, P -P as well as the S-P submanifolds of the n = 2 hydrogen states.…”

Divergence of the R−1 expansion for the second‐order H–H interaction

“…In treating the eigenvalue equation for H(O) + V, it is not necessary to consider electron spin. If the antisymmetry requirement is neglected [7], Vmay be treated as a perturbation on H(O). The unperturbed ground-state eigenfunction and eigenvalue are y'0' = 1Sa(1)1Sb (2), E(0) = -1…”

“…where 4 is any function orthogonal to y(O). Take (Note the similarity of ( 6 ) and (7) to quantities that enter the sum-over-states expression for y~~~o and E~~, . )…”

Long-Range Interactions for Hydrogen: 6P–1S and 6P–2S Systems

“…The long-range interaction of identical atoms, one of which is in an excited state, constitutes an interesting physical problem [1,2]. This is mainly due to energetic degeneracies connected with the "exchange" of the states among the two atoms.…”