An “electrons-in-molecule’' model for atom–atom representation of atom–molecule potentials, with application to the Ar–B2(X3Σg-) complex
Abstract
A flexible model for generating the anisotropic atom–atom form of an atom–diatom potential is developed and used to fit the high-level abinitio PES (potential energy surface) of the ground state Ar–B2 Van der Waals complex. The system is found to have only a well for the T-shaped geometry as a consequence of the sp-hybridisation of B within B2. Comparison of the complex with similar Ar–X2 species studied at the same level of theory exhibits some particular features of the boron system, originating from its electronic structure and interpreted in terms of the Ar–B interactions. A proper combination of the empirically adjusted potentials for isolated ArB and of the calculated effective atom–atom potentials acting in Ar–B2 is employed to produce the “real’' PES of the complex, used to predict its microwave spectrum.