Accurate long-range coefficients for two excited like isotope He atoms:He(2P1)–He(2P1),He(2P1)–He(2P3), andHe(2P3)–He(2P3)

J.-Y. Zhang, Z.-C. Yan, D. Vrinceanu, J. F. Babb, H. R. Sadeghpour
2007 Physical Review A. Atomic, Molecular, and Optical Physics  
A general formalism is used to express the long-range potential energies in inverse powers of the separation distance between two like atomic or molecular systems with P symmetries. The long-range molecular interaction coefficients are calculated for the molecular symmetries Δ, Π, and Σ, arising from the following interactions: He(2 ^1P)--He(2 ^1P), He(2 ^1P)--He(2 ^3P), and He(2 ^3P)--He(2 ^3P). The electric quadrupole-quadrupole term, C_5, the van der Waals (dispersion) term C_6, and
more » ... der terms, C_8, and C_10, are calculated ab initio using accurate variational wave functions in Hylleraas coordinates with finite nuclear mass effects. A comparison is made with previously published results where available.
doi:10.1103/physreva.76.012723 fatcat:nybagtv36ret5gejl22pcyycxq