Stabilization calculation of the energy and lifetime of metastable SO42−

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Abstract
It is known that SO42- is not electronically stable as an isolated species but can be rendered stable by solvation (e.g., by adding a few H2O molecules). Recently, our group introduced a Coulomb repulsion model that offers an approximation to the energy instability and lifetimes of such species. In order to achieve an independent and likely more reliable estimate of the instability of SO42-, we have undertaken a follow-up study of this dianion. Specifically, we apply a stabilization method to determine the vertical electronic energy difference between the metastable SO42- dianion and its SO4-1 daughter at several levels of theory. The particular variant of the stabilization method used here involves adding a partial positive charge to the central sulfur nucleus in order to confine the escaping electron. Our coupled-cluster data, which represent our highest level of theory, suggest that SO42- is unstable by 1.1 eV and has a lifetime with respect to electron loss of 1.6x10(-10) s (our earlier estimates were 0.75 eV and 2.7x10(-8) s). (C) 2002 American Institute of Physics.