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Free keywords:
Ab initio calculations; High pressure; Superconductivity models; Boundary value problems; Equations of state
Abstract:
The Tang-Toennies potential for the weakly interacting systems H2 b3Σ+u, H–He 2Σ+, and He2 1Σ+g is extended down to the united atom limit of vanishing internuclear distance. A simple analytic
expression connects the united atom limiting potential with the Tang-Toennies potential in the well region. The new potential model is compared with the most recent ab initio calculations for all three
systems. The agreement is better than 20% (H2 and He2) or comparable with the differences in the
available ab initio calculations (H–He) over six orders of magnitude corresponding to the entire range of internuclear distances.
