Quantum dynamics study of the dissociative photodetachment of HOCO-.

Six-dimensional wave packet calculations are carried out to study the behavior of HOCO subsequent to the photodetachment of an electron from the negative anion, HOCO-. It is possible to form stable and/or long-lived HOCO complexes, as well as the dissociative products OH+CO and H+CO2. A variety of observables are determined: the electron kinetic energy (eKE) distributions associated with the OH+CO and H+CO2 channels, the correlated eKE and product translational energy distribution for the OH+CO channel, and product branching ratios.

Quantum wave packet and quasiclassical trajectory studies of OH+CO: influence of the reactant channel well on thermal rate constants.

We study the OH+CO-->H+CO2 reaction with both six-dimensional quantum wave packets (QM) and quasiclassical trajectories (QCT), determining reaction probabilities and thermal rate constants (or coefficients), and studying the influence of the reactant channel hydrogen-bonded complex well on the reaction dynamics. The calculations use the recently developed Lakin-Troya-Schatz-Harding (LTSH) ground electronic state potential energy surface, along with a modified surface developed for this study (mod-LTSH), in which the reactant channel well is removed. Our results show that there can be significant differences between the QM and QCT descriptions of the reaction for ground-state reactants and for energies important to the thermal rate constants.

A new expression for the direct quantum mechanical evaluation of the thermal rate constant.

Based on the formalism of Miller, Schwartz, and Tromp [J. Chem. Phys.

Computer simulation of water in cytochrome c oxidase.

Statistical mechanics and molecular dynamics simulations have been carried out to study the distribution and dynamics of internal water molecules in bovine heart cytochrome c oxidase (CcO). CcO is found to be capable of holding plenty of water, which in subunit I alone amounts to about 165 molecules. The dynamic characterization of these water molecules is carried out.

Electron transfer in ferredoxin: are tunneling pathways evolutionarily conserved?

A theoretical study of electron transfer (ET) pathways in a recently crystallized Clostridium acidurici ferredoxin is reported. The electronic structure of the protein complex is treated at the semiempirical extended Hückel level, and the tunneling pathways are calculated with the rigorous quantum mechanical method of tunneling currents. The model predicts two pathways between the two [4Fe-4S] cubanes: a strong one running directly from Cys(14) to Cys(43) and a weaker one from Cys(14) via Ile(23) to Cys(18), whereas other amino acids do not play a significant role in the electron tunneling.