Matches in UGent Biblio for { <https://biblio.ugent.be/publication/3002717#aggregation> ?p ?o. }
Showing items 1 to 23 of
23
with 100 items per page.
- aggregation classification "C3".
- aggregation creator person.
- aggregation date "2012".
- aggregation hasFormat 3002717.bibtex.
- aggregation hasFormat 3002717.csv.
- aggregation hasFormat 3002717.dc.
- aggregation hasFormat 3002717.didl.
- aggregation hasFormat 3002717.doc.
- aggregation hasFormat 3002717.json.
- aggregation hasFormat 3002717.mets.
- aggregation hasFormat 3002717.mods.
- aggregation hasFormat 3002717.rdf.
- aggregation hasFormat 3002717.ris.
- aggregation hasFormat 3002717.txt.
- aggregation hasFormat 3002717.xls.
- aggregation hasFormat 3002717.yaml.
- aggregation language "eng".
- aggregation subject "Chemistry".
- aggregation title "Blocking channels for electron delocalization: an ab initio BRE?".
- aggregation abstract "Basic quantum chemical lore associates the molecular energy with a wave function and a Hamiltonian operator through the definition of an expectation energy. The wave function is obtained through one of many methods including Hückel's theory, Hartree-Fock theory, configuration interaction and so on. In variational methods, some parameters are varied until a minimum in energy is obtained. All properties of interest can then be obtained from the resulting wave function using a Hermitian operator. We have previously shown how one can measure electron delocalization through e.g., electron delocalization indices [1]. In (nearly) all cases the fully relaxed wave function is used. However, often it would be interesting to know "what if...". What if we could eliminate a circuit from an "aromatic" or generally delocalized system, what if we could switch off a bond etc. ? One possible answer is to look at valence bond theory. However, this theory is (somewhat unfortunately) much less popular than the more commonly used molecular orbital theory. In this talk we explore a different approach. The energy expression of a single Slater determinant consisting of all orthonormal orbitals is given by a well known expression where in the variational optimum the orbitals in the determinant are the N lowest energy spin orbitals (N=number of electrons) as produced with the Fock operator eigenequations. One can, however, also use an operator with an added potential to possibly constrain some expectation value [2]. Such method was recently applied by the author and co-workers for electronegativity equalization schemes [3-4]. Examples will be given on the energetic impact of blocking a possible delocalizing bond. What happens with the energy if we force a double bond to disappear ? And how does this relate to the graph theoretical BRE idea ? References [1] Bultinck, P.; Ponec, R.; Van Damme, S. J. Phys. Org. Chem., 2005, 18, 706-718. [2] Wu, Q.; Van Voorhis T. Phys. Rev. A, 2005, 72, 24502. [3] Bultinck, P.; Langenaeker, W.; Lahorte, P.; De Proft, F.; Geerlings, P.; Waroquier, M.; Tollenaere, J.P. J. Phys. Chem. A, 2002, 106, 7887-7894. [4] Verstraelen, T.; Bultinck, P.; Van Speybroeck, V.; Ayers, P.W.; Van Neck, D.; Waroquier, M. J. Chem. Theor. Comput., 2011, 7, 1750-1764. [5] Cedillo, A.; Van Neck, D.; Bultinck, P. Theor. Chem. Acc., 2012.".
- aggregation authorList BK248432.
- aggregation isDescribedBy 3002717.
- aggregation similarTo LU-3002717.