title: Theoretical Study of the Pyridine-Helium van der Waals Complexes.
abstract: In this study we evaluate a high-level ab initio ground-state intermolecular potential-energy surface for the pyridine-He van der Waals complex, using the CCSD(T) method and Dunning's augmented correlation consistent polarized valence double-ζ basis set extended with a set of 3s3p2d1f1g midbond functions. The potential is characterized by two symmetric global minima of -93.2 cm(-1) that correspond to geometries where the distance between the helium atom and the pyridine center of mass is 3.105 Å and the angle with respect to the pyridine c rotational axis is 3.9°. Six local minima can be observed for geometries with the helium atom in the plane cotaining the pyridine molecule. To further analyze the nature of the intermolecular interactions in the complex, we use symmetry-adapted perturbation theory (SAPT). Additional consideration of the pyridine-He2 complex provides a better insight into many-body nonadditive contributions to intermolecular interactions in systems with more helium atoms.
authors.affiliation: Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University , Grudziadzka 5, 87-100 Torun, Poland.|Department of Applied Mathematics and Computer Science, Technical University of Denmark , 2800 Kgs. Lynbgy, Denmark.|Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials (CIQUS), University of Santiago de Compostela , 15782 Santiago de Compostela, Spain.
authors.forename: Hubert
authors.initials: H
authors.lastname: Cybulski
authors.affiliation: Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University , Grudziadzka 5, 87-100 Torun, Poland.|Department of Applied Mathematics and Computer Science, Technical University of Denmark , 2800 Kgs. Lynbgy, Denmark.|Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials (CIQUS), University of Santiago de Compostela , 15782 Santiago de Compostela, Spain.
authors.forename: Christian
authors.initials: C
authors.lastname: Henriksen
authors.affiliation: Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University , Grudziadzka 5, 87-100 Torun, Poland.|Department of Applied Mathematics and Computer Science, Technical University of Denmark , 2800 Kgs. Lynbgy, Denmark.|Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials (CIQUS), University of Santiago de Compostela , 15782 Santiago de Compostela, Spain.
authors.forename: Berta
authors.initials: B
authors.lastname: Fernández