Electron density Laplacian and halogen bonds

In this paper, we discuss the physical meaning of the electron density Laplacian values in the valence region of halogen atoms and its relevance for the interpretation of halogen bonds formation. To this aim, formal relationships between Laplacian, electrostatic potential and molecular energies are derived, in particular within the framework of Bader's atoms-in-molecules theory. Simple one-dimensional models are finally provided to illustrate the semiquantitative usefulness of such tools.