SEARCH Articles Figures Tables A-expansion Atom approach Atomic shell Atoms and molecules Atoms shell Computational approaches Computational molecule Computer algebra Computer, the Derivative Approach Expansions for Goldstone Molecules atomizing Molecules atoms Molecules perturbative Open atomizer Open shell Open shell atoms Open-shell molecules Perturbation expansion Perturbation expansions Feynman-Goldstone Perturbational approaches Perturbative approach Perturbative expansion The expansion The perturbation approach The perturbation expansion