Functional groups expressed as graphs extracted from the Laplacian of the electron density
Paul L. A. Popelier, James R. Burke, Nathaniel O. J. Malcolm · International Journal of Quantum Chemistry · 2003
Abstract The valence charge concentration shell, as determined by the Laplacian of the electron density, is used as a source of quantum topological graphs, called L‐graphs. A considerable number of such graphs are extracted from theab initiowave functions of 31 molecules calculated at the B3LYP/6‐311+G(2d,p)//B3LYP/6‐311+G(2d,p)level, covering common functional groups in organic chemistry. We show how L‐graphs can be constructed from a largely transferable subgraph called atomic L‐graph. We investigate the topological stability of the L‐graphs as a function of the basis set. Reliable and consistent atomic L‐graphs are only obtained with basis sets of triple‐zeta quality or higher. The recurrence of invariant motifs or subgraphs in the L‐graphs enables the isolation of 16 atomic L‐graphs. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003