The aniline-argon van der Waals complex: ab initio second-order Moller-Plesset study of the potential energy surface in the ground electronic state

The potential energy surface of the aniline-argon (An-Ar) complex in the ground electronic state has been investigated by ab initio calculations using second-order Moller-Plesset (MP2) theory. The basis sets for the aromatic molecule and for the argon atom were cc-pvdz and aug-cc-pvtz, respectively. The structure in which the argon atom is opposite to the amino hydrogens (anti conformer) is found to be mon stable than the structure in which the argon atom and the amino hydrogens are on the same side of the ring (syn conformer). The calculated binding energies for the two conformers are 407 and 393 cm(-1), respectively. The introduction of diffuse orbitals for the aniline molecule using an aug-cc-pvdz basis set does not affect the relative stability of the two conformers. The calculated intermolecular distance, structure and rotational constants of the An-Ar complex reproduce satisfactorily the experimental data.