16 Topological Mechanochemistry of Graphene
299
fixation of edge atoms does not cause changing in both the map appearance and
absolute N DA value. However, the molecule becomes non-planar, which greatly
influences further deformation. Thus, in due course of the armchair-mode tension,
the difference in the values of eight framing basal atoms and remainders is gradually
smoothed, once equalizing at the 19th step. The situation remains the same for the
20th step in spite of the presence of the stretched C–C bonds. The bond breaking
occurs at the 21st step; the sample becomes radicalized with a small area of the
radical concentration. Oppositely to the case, the zigzag-mode deformation does not
cause any smoothing of the N DA values distribution and keeps the non-deformed
shape up to the 19th step. The bond stretching is observed at the steps from 17th to
19th, and the bond breaking occurs at the 20th step.
Taking together, Figs. 16.5, 16.7, 16.9, and 16.10 exhibit changing in the odd
electron correlation of the graphene molecule under deformation and highlight a
strong dependence of the correlation on both the deformational mode configuration
and the chemical modification of the molecule edge atoms.
16.5 Conclusion
Presented in the current chapter undoubtedly shows that the chemical modification
of the graphene molecule edge atoms has a great impact on its mechanical behavior. The feature results from the significant correlation of the molecule odd electrons followed by their conjugation over the molecule. Thus, the transition from the
naked molecule, characterized by the maximal correlation of the odd electrons, to
the molecule with the single- and double-hydrogen-terminated edges is followed by
a considerable suppression of the correlation related to the edge atoms in the former case and a complete zeroing of the latter in the second case. As turned out, the
changes are not local and strongly influence the electronic structure in the region of
the basal plane, where the main deformational process occurs, causing the redistribution of the C–C bonds over their lengths, thus, changing ‘the quality’ of the bonds
and providing the topological character of the deformational processes in graphene.
Acknowledgements A financial support provided by the Ministry of Science and High Education of the Russian Federation grant 2.8223.2013 is highly acknowledged.
References
1. Cataldo F, Graovac A, Ori O (eds) (2011) The mathematics and topology of fullerenes.
Springer Science+Business Media BV, Berlin
2. Merrifield RE, Simmons HE (1989) Topological methods in chemistry. Wiley, New York
3. Schmidt GMJ (1971) Photodimerization in the solid state. Pure Appl Chem 27:647–678
4. de Jong AWK (1923) Uber die Konstitution der Truxill – und Truxinsauren und uber die
Entwiklung des Sonnenlichtes auf die Zimtsauren und Zimisaure – Salze. Chem Ber 56B:818–
832
299
fixation of edge atoms does not cause changing in both the map appearance and
absolute N DA value. However, the molecule becomes non-planar, which greatly
influences further deformation. Thus, in due course of the armchair-mode tension,
the difference in the values of eight framing basal atoms and remainders is gradually
smoothed, once equalizing at the 19th step. The situation remains the same for the
20th step in spite of the presence of the stretched C–C bonds. The bond breaking
occurs at the 21st step; the sample becomes radicalized with a small area of the
radical concentration. Oppositely to the case, the zigzag-mode deformation does not
cause any smoothing of the N DA values distribution and keeps the non-deformed
shape up to the 19th step. The bond stretching is observed at the steps from 17th to
19th, and the bond breaking occurs at the 20th step.
Taking together, Figs. 16.5, 16.7, 16.9, and 16.10 exhibit changing in the odd
electron correlation of the graphene molecule under deformation and highlight a
strong dependence of the correlation on both the deformational mode configuration
and the chemical modification of the molecule edge atoms.
16.5 Conclusion
Presented in the current chapter undoubtedly shows that the chemical modification
of the graphene molecule edge atoms has a great impact on its mechanical behavior. The feature results from the significant correlation of the molecule odd electrons followed by their conjugation over the molecule. Thus, the transition from the
naked molecule, characterized by the maximal correlation of the odd electrons, to
the molecule with the single- and double-hydrogen-terminated edges is followed by
a considerable suppression of the correlation related to the edge atoms in the former case and a complete zeroing of the latter in the second case. As turned out, the
changes are not local and strongly influence the electronic structure in the region of
the basal plane, where the main deformational process occurs, causing the redistribution of the C–C bonds over their lengths, thus, changing ‘the quality’ of the bonds
and providing the topological character of the deformational processes in graphene.
Acknowledgements A financial support provided by the Ministry of Science and High Education of the Russian Federation grant 2.8223.2013 is highly acknowledged.
References
1. Cataldo F, Graovac A, Ori O (eds) (2011) The mathematics and topology of fullerenes.
Springer Science+Business Media BV, Berlin
2. Merrifield RE, Simmons HE (1989) Topological methods in chemistry. Wiley, New York
3. Schmidt GMJ (1971) Photodimerization in the solid state. Pure Appl Chem 27:647–678
4. de Jong AWK (1923) Uber die Konstitution der Truxill – und Truxinsauren und uber die
Entwiklung des Sonnenlichtes auf die Zimtsauren und Zimisaure – Salze. Chem Ber 56B:818–
832