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A new scheme for general classification of quantum objects is presented. Based on molecular quantum similarity matrices (MQSM), different algorithms are presented for generating Molecular Quantum Similarity Dendrograms (MQSD). An application of MQSD is presented for a set of steroid molecules.

The use of the molecular quantum similarity overlap measure for molecular alignment is investigated. A new algorithm is presented, the quantum similarity superposition algorithm (QSSA), expressing the relative positions of two molecules in terms of mutual translation in three Cartesian directions and three Euler angles. The quantum similarity overlap is… (More)

The calculation of molecular quantum similarity measures using the molecular electron density requires the electron density and molecular alignment between two molecules. To obtain meaningful quantum similarity matrices, the electron density should be calculated efficiently and accurately and the alignment should be internally consistent. The internal… (More)

Auxins are defined mainly by a set of physiological actions, but the structure-effect relationship still is based on chemical intuition. Currently a well-defined auxin molecular structure is not available. The existence of different auxin binding proteins and mechanisms of auxin action, the wide diversity of the auxin molecules, and the pleiotropic effects… (More)

- Brecht Verstichel, References, B Verstichel, H Van Aggelen, D Van Neck, P W Ayers +7 others
- 2010

The variational determination of the density matrix is a technique to determine the ground-state properties of a many-body system without reference to the wave function. The energy is minimized as a function of the second-order density matrix Γ, on the condition that it remains N-representable, i.e. Γ αβ;γδ = Ψ N |a † α a † β a δ a γ |Ψ N. There are several… (More)

The aromaticity and local-aromaticity of a large set of polycyclic aromatic hydrocarbons (PAHs) is studied using multicenter delocalization indices from generalized population analysis and the popular nucleus independent chemical shift (NICS) index. A method for the fast computation of the NICS values is introduced, using the so-called pseudo-pi-method. A… (More)

A large number of local aromaticity indices for the benzenoid rings in polyaromatic hydrocarbons is computed. The results are interpreted, supporting Clar's hypothesis, and mutual correlations are investigated. It is shown that there are good correlations between all indices that strictly allow comparing benzenoid character. Poor correlations are found with… (More)

Molecular aromaticity in the linear polyacenes is investigated using an atoms in molecules based six center index (SCI-AIM) which measures the electron delocalization. SCI-AIM values for the linear polyacenes indicate decreasing aromaticity going from outer to inner rings in the polyacene series. The SCI-AIM approach is compared to a Mulliken-like approach,… (More)

- P Bultinck, R Vanholme, P L A Popelier, F De Proft, P Geerlings

The applicability of the electronegativity equalization method (EEM) is investigated for the calculation of atoms-in-molecules charges in prototypical organic molecules. A large training set of molecules was composed, comprising H, C, N, O, and F. Geometries and atomic charges are calculated at the B3LYP/6-31G* level, and from the calculated charges,… (More)

This study presents an alternative of the Electronegativity Equalization Method (EEM), where the usual Coulomb kernel has been transformed into a smooth function. The new framework, as the classical EEM, permits fast calculations of atomic charges in a given molecule for a small computational cost. The original EEM procedure needs to previously calibrate… (More)