The lowest energy (II2,1,0+,0-)-I-3 and (3)Sigma(+)(1,0-) excited states of the MgNe van der Waals molecule

We report ab initio calculations of the lowest (3)Pi, and (3)Sigma(+) excit ed states of the MgNe van der Weals molecule correlating with Mg(3s3p(3)P(0 ,1,2)) + Ne(2p(6 1)S(0)). The spin-orbit multiplet potential curves of thes e states were estimated using the atomic spin-orbit coupling constant. Beca use of spin-orbit induced Sigma/Pi mixing, an extremely shallow potential c urve is found for the lowest (3)Pi(0-) level (D-0 = 3 cm(-1)), perhaps expl aining why we have been unable to prepare the Mg(3s3p (3)p(0)). Ne((3)Pi(0- )) state experimentally. The van der Waals bonding in the Mg(3s3p pi) RG((3 )Pi) states is compared with that in the analogous Na(3p pi). RG[(2)Pi] and Al(3s(2)3p pi). RG[(2)Pi] states. (C) 1999 Elsevier Science B.V. All right s reserved.