Coulomb-stable triply charged diatomic: HeY3+

Accurate relativistic coupled-cluster calculations show that the triply cha rged species HeY3+ is a stable molecule and represents the lightest diatomi c trication that does not undergo a Coulomb fragmentation into charged frag ments. The diatomic potential-energy curve is approximated by an extended M orse potential, and vibrational-rotational constants for HeY3+ are predicte d (R-e = 224.3 pm, D-0 = 0.394 eV, omega(e) = 437 cm(-1), omega(e)x(e) = 15 .8 cm(-1), B-e = 0.877 cm(-1)). It is further shown that the He-Y3+ bond ca n basically be described as a charge-induced dipole interaction. [S1050-294 7(99)50711-7].