COMPARATIVE-STUDIES OF THE LOWEST SINGLET-STATES OF (O-2)(2) INCLUDING AB-INITIO CALCULATIONS OF THE 4 EXCITED-STATES DISSOCIATING INTO O-2((1)TRIANGLE-G)-2((1)TRIANGLE-G)(O)

Ab initio calculations have been performed for the four singlet states of (O-2)(2) dissociating into O-2((1)Delta(g)) + O-2((1)Delta(g)). Th ey are compared with previous semi-ab initio perturbation calculations . A surprisingly good agreement in the potential behavior is observed between these two complementary treatments. After the recent work of M inaev et al., these are the first ab initio calculations of the excite d states of the dimer, corrected for basis set superposition errors (B SSE) and evaluated in a size consistent way. Though a similar behavior of the potential with the intermolecular distance has been observed b y Minaev et al., discrepancies remain in the binding energies of the d imer. (C) 1998 American Institute of Physics.