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 gr ound 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 a rgon atom and the amino hydrogens are on the same side of the ring (syn con former). The calculated binding energies for the two conformers are 407 and 393 cm(-1), respectively. The introduction of diffuse orbitals for the ani line molecule using an aug-cc-pvdz basis set does not affect the relative s tability of the two conformers. The calculated intermolecular distance, str ucture and rotational constants of the An-Ar complex reproduce satisfactori ly the experimental data. (C) 1999 Elsevier Science B.V. All rights reserve d.