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The calculation of the electron localization function (ELF) at the correlated level carries the computational
 
The calculation of the electron localization function (ELF) at the correlated level carries the computational
expense of the second-order density matrix (DM2).<sup>1</sup> In this work we suggest the use an approximations for
+
expense of the second-order density matrix (DM2).<sup>1</sup> In this work we put forward an approximations for
the calculation of the DM2 in order to considerably reduce the computational effort.<sup>2</sup>
+
the calculation of the ELF at the correlated level without using the DM2.<sup>2</sup>
In particular, we use the expression for monodeterminantal wavefunctions and the formula of Müller in terms of
+
In particular, we use the approximate expressions based on the formula for the monodeterminantal wavefunctions
natural orbitals.<sup>3</sup> The approximation has been tested in a set of molecules,
+
and the formula of Müller in terms of natural orbitals.<sup>3</sup>
 +
The approximation has been tested in a set of molecules,
 
NH<sub>3</sub>, CO<sub>2</sub>, H<sub>2</sub>O, CO, CN<sup>-</sup>, NO<sup>+</sup>, N<sub>2</sub>,  
 
NH<sub>3</sub>, CO<sub>2</sub>, H<sub>2</sub>O, CO, CN<sup>-</sup>, NO<sup>+</sup>, N<sub>2</sub>,  
 
H<sub>2</sub>O<sub>2</sub>, F<sub>2</sub> and FCl<sup>-</sup>, which have been calculated using a plethora of
 
H<sub>2</sub>O<sub>2</sub>, F<sub>2</sub> and FCl<sup>-</sup>, which have been calculated using a plethora of
methods: HF, B3LYP, MP2, CISD, CCSD and CASSCF. For these methods/molecules we calculate atomic population and its
+
methods: HF, B3LYP, MP2, CISD, CCSD and CASSCF. For these methods/molecules we calculate the atomic population and its
 
variance for each ELF basin.
 
variance for each ELF basin.
  

Version du 20 mai 2010 à 16:19

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SPEAKERS : please add below, in your own section, your title talk and abstract :

  • click on your name in the "Contents" box below, this will lead you to your own section;
  • your section starts with your name as the title line, click on [edit] (far right).


The order of abstract follow the program of the workshop.


E. Alikhani

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P. Hiberty

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C. Lepetit

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M-M. Rohmer

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B. De Courcy

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H. Jamet

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G. A. Cisneros

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X. Assfeld

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H. S. Rzepa

Department of Chemistry, Imperial College London

ELF and the Nature of Triple bonds

A recent report of the species HOS≡CH by Schreiner, Mloston and co-workers1 speculated upon the nature of the SC bond; did it have triple significant bond character? Of the various techniques these authors used for the analysis, neither QTAIM nor ELF was employed. I initially filled this gap by a post on my blog2, and followed this by a full article submitted for publication more conventionally3. The results of this investigation will be presented at the workshop, including a rather surprising conclusion regarding the nature of triple bonds themselves in relation to the degree of charge-shift character they display4. The hypothesis so generated was then extended to investigating the nature of metal-metal multiple bonds, particularly Cr-Cr whose compounds are purported to exhibit homonuclear quadruple or quintuple bonds5. These systems also appear to sustain remarkably high charge-shift character and most intriguing ELF behaviour. The issue for discussion in the workshop is therefore whether or not ELF (combined with QTAIM) is indeed revealing something new about the nature of the triple and higher order homonuclear (metal) bond.

The talk will appear @www.ch.ic.ac.uk/rzepa/talks/elf10 and will feature rotatable ELF isosurfaces and models.

Cr-Cr quintuple bond

References

[1] P. R. Schreiner, H. P. Reisenauer, J. Romanski, and G. Mloston, Angew. Chemie. 2009, 48, 8133-8136. DOI: 10.1002/anie.200903969

[2] H. S. Rzepa, Blog and follow up

[3] H. S. Rzepa, submitted for publication, 2010.

[4] S. Shaik, D. Danovich, W. Wu and P. C. Hiberty, Nature Chem., 2009, 1, 443-449. DOI: 10.1038/nchem.327

[5] For initial speculations, see blog.

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M. Yanez

Departamento de Química, C-9. Universidad Autónoma de Madrid. Cantoblanco, 28049-Madrid. Spain

ELF as a useful tool to understand chemical bonding in challenging cases

Quite unexpectedly, substituent effects on the structure of iminoboranes are opposite to those observed for the acetylene derivatives in spite of the fact that both series of compounds are isoelectronic. [1] More importantly these dissimilarities cannot be easily explained in terms of the atoms in molecules (AIM) theory or in terms of the population of the πBN* or πCC* antibonding orbitals. In some molecules a decrease (increase) of the electron density is unexpectedly reflected in a shortening (lengthening) of the bond. Conversely, the ELF analysis offers a clear picture of the substituent effects on the CC and BN bonding. The dissimilarities between acetylene- and iminoborane derivatives are primarily a consequence of the strong electronegativity difference between the B and N atoms in the iminoboranes. This difference is the origin of the significant distortion of the BN bonding electron density in iminoboranes, which is not seen in the corresponding acetylene analogues.

References

[1] O. Mó; M. Yáñez; A. Martín Pendás; J.E. Del Bene; I. Alkorta and J. Elguero, Phys. Chem. Chem. Phys. 9, 3970 (2007)


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P. J. MacDougall

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J. Angyan

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M. Causa

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J. Contreras-Garcia

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D. L. Cooper

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A. Lüchow

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E. P. Fowe

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S. Grabowski

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A. M. Pendas

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E. Matito

Institute of Physics, University of Szczecin, Poland

The Electron Localization Function at the Correlated Level: A Natural Orbital Formulation.

The calculation of the electron localization function (ELF) at the correlated level carries the computational expense of the second-order density matrix (DM2).1 In this work we put forward an approximations for the calculation of the ELF at the correlated level without using the DM2.2 In particular, we use the approximate expressions based on the formula for the monodeterminantal wavefunctions and the formula of Müller in terms of natural orbitals.3 The approximation has been tested in a set of molecules, NH3, CO2, H2O, CO, CN-, NO+, N2, H2O2, F2 and FCl-, which have been calculated using a plethora of methods: HF, B3LYP, MP2, CISD, CCSD and CASSCF. For these methods/molecules we calculate the atomic population and its variance for each ELF basin.

Profile for CO molecule along the molecular axis. Left (R=1.23A). Right (R=2.0A)


References

[1] Matito E., Silvi B., Duran M. and Solà M., J. Chem. Phys. 125, 024301 (2006)

[2] Feixas F., Matito E., Duran M., Solà M. and Silvi B., in preparation.

[3] Müller A.M.K., Phys. Lett. 105A, 446 (1984)


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D. Borgis

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R. Vuillemier

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J. Cioslowski

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J. Pilmé

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R. Nesper

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Y. Grin

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J-F. Halet

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U. Wedig

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R. Weihrich

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P. Raybaud

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E. Dumont

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N. Chéron

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S. Berski

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L. Joubert

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H. Bolvin

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A. Delalande

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R. Nalewajski

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A. Scemama

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J. Tao

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I. Fourré

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H. Gérard

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N. Russo

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