Study of the benzene•N2 intermolecular potential-energy surface

The intermolecular potential-energy surface pertaining to the interaction between benzene and N-2 is investigated theoretically and experimentally. Accurate intermolecular interaction energies are evaluated for the benzene-N-2 van der Waals complex using the coupled cluster singles and doubles including connected triples [CCSD(T)] method and the aug-cc-pVDZ basis set extended with a set of 3s3p2d1f1g midbond functions. After fitting the energies to an analytic function, the intermolecular Schrodinger equation is solved to yield energies, rotational constants, and Raman-scattering coefficients for the lowest intermolecular levels of several benzene-N-2 isotopomers. Experimentally, intermolecular Raman spectra of jet-cooled h(6)- and d(6)-benzene-N-2 measured at 0.03 cm(-1) resolution by mass-selective, ionization-detected stimulated Raman spectroscopies are reported. Seven intermolecular bands are assigned for each isotopomer, including transitions involving intermolecular bending and stretching vibrations and internal rotation about the benzene C-6 axis. These Raman data, together with measured rotational constants and binding energies obtained by other groups on benzene-N-2, agree well with the theoretical results. Such agreement points to the promise of the quantum chemical methodology employed herein in future investigations of larger van der Waals complexes. (C) 2003 American Institute of Physics.