A numerical method for the topological analysis of the Laplacian of the electronic charge density in molecules and solids

A numerical method that analyzes the topology of the Laplacian of the electronic density regardless of how it was obtained (analytically, numerically, or even experimentally) was implemented for the BUBBLE program. The method allows the study of a complex system where the electronic correlation is important, by density functional theory regardless the kind of basis set used, and allows the analysis of the Laplacian of the resulting charge density with the topological theory of Bader. The method was applied to CO and NO molecules and the Cu-13, Cu-45, and Fe-21 clusters modeling the (100) Cu and (001) Fe surfaces, respectively.