Abstract :
Diatomics-in-molecule models of different levels of accuracy are developed for the RgX2− systems, involving the complete set of X2− states originating from the X(2P3/2,1/2) + X−(1S0) interaction, and applied to the specific case of the ArI2− complex. The ground and lowest excited state Ar–I2− potentials are found to be affected weakly by both spin-orbit coupling and mixing of different states of I2− by Ar. This allows for accurately reproducing the system potential energy surfaces (PES) by simple analytic functions corresponding to separate states of I2− treated diabatically. In addition to the standard DIM approach, interaction of the induced dipole on Ar with the induced dipole and permanent quadrupole on I is taken into account. This is found to affect significantly the Ar–I2− ground state PES topology by decreasing binding for both linear and T-shaped geometries, thus resulting in a single major T-well. Vibrational frequencies and electron affinity shifts are predicted. The frequencies are found to be close to those for ArI2 in spite of about double increase of binding, and the shifts are significantly reduced relative to those for ArI. Interpretations of the obtained relations are discussed.
