Computational Chemistry

(Steven Felgate) #1

The question of the possible breaking of a C–H bond here in preference to inversion
has been considered [2].


References



  1. Ter-Akopian GM et al (2002) American Institute of Physics Conference Proceedings, April 22,
    vol 610, p 920. Nuclear physics in the 21st century: International nuclear physics conference
    INPC 2001; DOI:10.1063/1.1470062

  2. Lewars E (2008) Modeling marvels. Computational anticipation of novel molecules. Springer,
    New York, chapter 1, Planar Carbon, Introduction


Chapter 2, Harder Questions, Answers


Q9


Only certain parts of a PES are chemically interesting: some regions are flat and
featureless, while yet other parts rise steeply and are thus energetically inaccessible.
Explain.
Chemically interesting regions of a PES are areas where relative minima and the
transition states connecting them reside, that is, where chemistry takes place.
Rarely-explored are parts where nothing happens or too much happens.
Nothing happens where a molecule has been broken into its component
atoms and these atoms are widely separated and thus noninteracting – these are
plateau regions (compare question 7). Here the reaction coordinate is simply a
composite of the interatomic separations and altering these has no effect on the
energy.
Too much happens in regions where molecules or parts of molecules are
squeezed strongly together: here the energy changes very steeply with changes in
the reaction coordinate, rising sharply as intermolecular or nonbonded atomic
distances decrease. Actually, these regions might be of interest in molecular
dynamics studies of reactions under very high pressures [1–3].


References



  1. Molecular dynamics, review: Frank I (2003) Angew. Chem Int Ed Engl 42:1569

  2. Molecular dynamics, review: Tuckerman ME, Martyna GJ (2000) J Phys Chem B 104:159

  3. Molecular dynamics study of the conversion of methane to diamond under pressure: Scandolo
    S, Jeanloz R (2003) American Scientist 91:516


Answers 601

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