Dresden 2003 – wissenschaftliches Programm

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SYCN: Computational nanoscience - from materials to biology

SYCN 102: Computational Nanoscience: From Materials to Biology (Poster, gemeinsam mit SYSE)

SYCN 102.15: Poster

Dienstag, 25. März 2003, 19:00–21:00, ZEU/160

Calculating the mechanical strength of a covalent bond — •Martin Beyer — Institut fuer Physikalische und Theoretische Chemie, Technische Universitaet Muenchen, Lichtenbergstrasse 4, 85747 Garching

The rupture forces of covalent bonds in a polymer as a function of bond lifetime are calculated with an Arrhenius kinetics model based on high-level density functional theory calculations [1] and compared with measurements from atomic force microscopy [2]. Relaxed potential energy surface scans of small model molecules yield potential functions that account for the deformations and hybridizations caused by the application of force. Morse potentials chosen to exhibit the same well depth and maximum force are used as an analytic representation of an individual bond in an infinitely long one-dimensional polymer. Application of force deforms the potential, and the activation energy for the bond rupture event together with the frequency of an optical phonon in the one-dimensional polymer are the two Arrhenius parameters. Rupture forces of the bonds C-C, C-N, C-O, Si-C, Si-N, Si-O, and Si-Si are reported as a function of the lifetime of the bond.

[1] M. K. Beyer, J. Chem. Phys. 112, 7307-7312 (2000).

[2] M. Grandbois, M. Beyer, M. Rief, H. Clausen-Schaumann, and H. E. Gaub, Science 283, 1727-1730 (1999).