https://zenodo.org/record/1258475/files/article.pdf

Electron transfers in chemistry and biology

N G van Kampen 1981 Amsterdam: North-Holland xiv + 419 pp price Dfl 180 This is a book which, at a lower price, could be expected to become an essential part of the library of every physical scientist concerned with problems involving fluctuations and stochastic processes, as well as those who just enjoy a beautifully written book. It provides an extensive graduate-level introduction which is clear, cautious, interesting and readable.

https://iopscience.iop.org/article/10.1088/0031-9112/34/4/040/pdf

Stochastic Processes in Physics and Chemistry

2.2. Materials 929 2.3. Factors Influencing Charge Mobility 931 2.3.1. Molecular Packing 931 2.3.2. Disorder 932 2.3.3. Temperature 933 2.3.4. Electric Field 934 2.3.5. Impurities 934 2.3.6. Pressure 934 2.3.7. Charge-Carrier Density 934 2.3.8. Size/molecular Weight 935 3. The Charge-Transport Parameters 935 3.1. Electronic Coupling 936 3.1.1. The Energy-Splitting-in-Dimer Method 936 3.1.2. The Orthogonality Issue 937 3.1.3. Impact of the Site Energy 937 3.1.4. Electronic Coupling in Oligoacene Derivatives 938

Charge transport in organic semiconductors.

T e purpose of this review is to assess the nature and magnitudes of the dominant forces in protein folding. Since proteins are only marginally stable at room temperature,’ no type of molecular interaction is unimportant, and even small interactions can contribute significantly (positively or negatively) to stability (Alber, 1989a,b; Matthews, 1987a,b). However, the present review aims to identify only the largest forces that lead to the structural features of globular proteins: their extraordinary compactness, their core of nonpolar residues, and their considerable amounts of internal architecture. This review explores contributions to the free energy of folding arising from electrostatics (classical charge repulsions and ion pairing), hydrogen-bonding and van der Waals interactions, intrinsic propensities, and hydrophobic interactions. An earlier review by Kauzmann (1959) introduced the importance of hydrophobic interactions. His insights were particularly remarkable considering that he did not have the benefit of known protein structures, model studies, high-resolution calorimetry, mutational methods, or force-field or statistical mechanical results. The present review aims to provide a reassessment of the factors important for folding in light of current knowledge. Also considered here are the opposing forces, conformational entropy and electrostatics. The process of protein folding has been known for about 60 years. In 1902, Emil Fischer and Franz Hofmeister independently concluded that proteins were chains of covalently linked amino acids (Haschemeyer & Haschemeyer, 1973) but deeper understanding of protein structure and conformational change was hindered because of the difficulty in finding conditions for solubilization. Chick and Martin (191 1) were the first to discover the process of denaturation and to distinguish it from the process of aggregation. By 1925, the denaturation process was considered to be either hydrolysis of the peptide bond (Wu & Wu, 1925; Anson & Mirsky, 1925) or dehydration of the protein (Robertson, 1918). The view that protein denaturation was an unfolding process was

/pdf/dominant-forces-in-protein-folding-42bjzlldw4.pdf

Dominant forces in protein folding

6. Rehybridization of the Acceptor (RICT) 3908 7. Planarization of the Molecule (PICT) 3909 III. Fluorescence Spectroscopy 3909 A. Solvent Effects and the Model Compounds 3909 1. Solvent Effects on the Spectra 3909 2. Steric Effects and Model Compounds 3911 3. Bandwidths 3913 4. Isoemissive Points 3914 B. Dipole Moments 3915 C. Radiative Rates and Transition Moments 3916 1. Quantum Yields and Radiationless Deactivation Processes 3916

Structural Changes Accompanying Intramolecular Electron Transfer: Focus on Twisted Intramolecular Charge-Transfer States and Structures

We present a critical scrutiny of the models for the primary charge separation process in bacterial photosynthesis in the light of recent experimental data and theoretical analysis. The sequential mechanisms are fraught with difficulties due to their incompatibility with magnetic data for the first observable radical pair in conjunction with the activationless nature of the electron transfer process. The implications of the unistep, superexchange mediated nonadiabatic electron transfer mechanism are examined.

Mechanism of the Primary Charge Separation in Bacterial Photosynthetic Reaction Centers

Medium stabilization of localized Born—Oppenheimer states

We address a central question in the realm of the dynamics of high-n (= 40- 250) Rydberg states of diatomics and large molecules. What is the coupling responsible for the 'global' l mixing, which results in the breakdown of the n 3 scaling law for the non-radiative lifetimes and for the lifetime lengthening (by two to four orders of magnitude) of these states? To explore the implications of intramolecular interactions on l mixing and on electronic-rotational energy exchange we analysed the intramolecular couplings of the ion core dipole, quadrupole and (anisotropic) polarizability with a non-penetrating (l⩾ 3) Rydberg electron, in conjunction with the energy gaps between proximal pairs of energy levels. Calculations of the energy gaps and the couplings were performed for the high-n non-penetrating Rydberg states of NO and for model 'light' (B = 19 cm-1) and 'heavy' (B = 0⋅05 cm-1) polar molecules. All the intramolecular interactions are of the form of a power law proportional to l -η, with η being determi...

Intramolecular coupling between non-penetrating high molecular Rydberg states

In this paper, we investigate the quantum dynamics of wave packets of bound states in the nonlinear Henon–Heiles (HH) system. The time evolution of a wave packet was separated into two processes involving (a) the motion of its first moments and (b) its spreading. On the time scale when wave packet spreading can be neglected, we were able to establish relations between wave packet quantum dynamics expressed in terms of the initial‐state population probability P(t) and classical trajectory dynamics. We have demonstrated that the initial states, which are characterized by a periodic time evolution of P(t) over many periods, are related to the five elliptic periodic orbits in the HH system. The decay of P(t) over a few vibrational periods is related to the classical features of quasiperiodic trajectories and can be accounted for in terms of overlap reduction effects. When the center of the initial wave packet is moved further away from the classical periodic orbits, P(t) is characterized by a single initial p...

Quantum dynamics of the Henon–Heiles system

In this paper we report the results of model calculations on the temperature dependence of the electron transfer (ET) rate from cytochrome C to the reaction center in the photosynthetic bacterium chromatium. The effects of both polar medium phonons and of molecular vibrations of the electron donor and the acceptor center were incorporated within the framework of a nonadiabatic multiphonon description of the ET process. The nuclear parameters required to account for the temperature dependence are in accord with the available physical and chemical information regarding this system, while the large electronic coupling indicates the possible role of intermediate states in the ET process.

Mordechai Bixon

Papers

Mechanism of the Primary Charge Separation in Bacterial Photosynthetic Reaction Centers

Medium stabilization of localized Born—Oppenheimer states

Intramolecular coupling between non-penetrating high molecular Rydberg states

Quantum dynamics of the Henon–Heiles system

Effects of medium modes on electron transfer in a biological system