T. Sommerfeld et al., Ab initio calculation of energies and lifetimes of metastable dianions: The C-2(2-) resonance, J CHEM PHYS, 112(15), 2000, pp. 6635-6642
Most small dianions known in the solid state and solutions cannot exist as
isolated entities and decay in the gas phase by electron autodetachment. Th
ese dianions show rare-gas-like closed-shell electronic ground states and r
epresent a new type of metastable system. Here we study the prototype close
d-shell resonance C-2(2-) in the framework of the complex absorbing potenti
al method. We investigate in detail a number of unsettled methodological is
sues. In particular, there is no "natural" choice of orbital set for closed
-shell metastable states and we study several orbital sets as well as other
basis set and correlation effects on resonance energy and width. Closed-sh
ell resonances typically show several open decay channels and we compute pa
rtial widths for the three open channels of C-2(2-). Finally, we study the
complex potential energy curve and compare our bond lengths and vibrational
frequencies with geometrical parameters which have been obtained ignoring
the metastable character of C-2(2-). (C) 2000 American Institute of Physics
. [S0021- 9606(00)30810-8].