The nature of the hydrogen bond from real space analyses

Prof. A. M. Pendás Universidad de Oviedo, Espagne

Mercredi, 29 février 2012, 11h00

The interacting quantum atoms approach (IQA) is applied to simple hydrogen bonded dimers. IQA [1,2] is a real space energy decomposition scheme fully compatible with the quantum theory of atoms in molecules.
It provides a partition of every physical term present in the Hamiltonian into atomic and interatomic terms [3]. The procedure is orbital-free and self-contained, needing neither external references nor artificial intermediate states. According to IQA, there is no incompatibility between the prevalent electrostatic image of hydrogen bonded systems and that favoring important covalent contributions.
Depending on how we gather the many different energetic terms, we may recover electrostatic or covalent pictures from the same underlying quantum mechanical description. Our results show that the non-classical contributions to hydrogen bonding are spatially localized, involving only the H atom and its two nearest neighbors. IQA may be also used to compare with other widely used decomposition schems. Such a comparison sheds some light on the virtues and faults of the different methods, and as well on the origin of the 50 years old debate regarding the covalent/electrostatic nature of the hydrogen bond [4].
References [1] A. Martín Pendás, M. A. Blanco, and E. Francisco, J. Chem. Phys., 120, 4581 (2004).
[2] A. Martín Pendás, E. Francisco, and M. A. Blanco, J. Comput. Chem., 26, 344 (2005) .
[3] M. A. Blanco, A. Martín Penás, and E. Francisco, J. Chem. Theory Comput. 1, 1096, (2005).
[4] A. Martín Penás, M. A. Blanco, and E. Francisco, J. Chem. Phys., 125, 184112 (2006).