MBPT STUDY OF THE CO-H-2 VAN-DER-WAALS INTERACTION

The many-body perturbation theory (MBPT) is employed for the calculation of the intermolecular interaction potential for the linear CO...H-2 dimer in the framework of the supermolecule approach, using the POL1 basis described recently by Sadlej. This basis set, designed to reproduce electric properties of molecules accurately, leads to a correct calculation of the counterpoise-corrected interaction energies, in excellent agreement with results obtained in the larger basis set used in this study for comparison, and with the best theoretical values available to date. The minimum of the MBPT(4) interaction energy curves occurs at 8.14 and 8.03 a(0), with well depths of 9.16 and 10.66 meV for the POL1 and larger basis set calculations, respectively. In agreement with very recent spectroscopic results, a vibrationally bonded ground state is also predicted for this linear dimer.