Rigid bridge model

We begin with a summary of the standard single-electron rigid-bridge model for electron transport [1,2], and then describe effects that arise from bridge dynamics. We next examine issues in multistep multi-center electron transfer. The closely related problem of two-electron transfer is then discussed. Multi-center and multielectron processes are of great relevance for ET in DNA, proteins, and catalytic reactions. 

M. Antolovich, P. J. Keyte, A M. Oliver, M. N. Paddon-Row, J. Kroon, J. W. Verhoeven, S. A Jonker, J. M. War-man, Modelling Long-Range Photosynthetic Electron Transfer in Rigidly Bridged Porphyrin-Quinone Systems ,/. Phys. Chem. 1991, 95,1933-1941. 

Seismic Analysis of Steel and Composite Bridges Numerical Modeling, Fig. 17 (a) Cranposition of reinforced elastomeric bearings, (b) Single DOF seismic analysis of a simply supported composite bridge with a rigid deck model... 

The essence of this model for the second virial coefficient is that an excluded volume is defined by surface contact between solute molecules. As such, the model is more appropriate for molecules with a rigid structure than for those with more diffuse structures. For example, protein molecules are held in compact forms by disulfide bridges and intramolecular hydrogen bonds by contrast, a randomly coiled molecule has a constantly changing outline and imbibes solvent into the domain of the coil to give it a very soft surface. The present model, therefore, is much more appropriate for the globular protein than for the latter. Example 3.3 applies the excluded-volume interpretation of B to an aqueous protein solution. 

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