Theoretical approaches for calculating rate constants of chemical reactionsseither the microcanonical rate for a given total energy k(E) or the canonical rate for a given temperature k(T)sare described that are both “direct”, i.e., bypass the necessity of having to solve the complete state-to-state quantum reactive scattering problem, yet also “correct”, i.e., in principle exact (given a potent...

A single-disulfide variant of bovine pancreatic trypsin inhibitor (BPTI), [14-38]Abu, is a partially folded ensemble which includes two, and in one case three, conformations that interconvert slowly enough to exhibit separate cross-peaks in the amide region of homonuclear and heteronuclear NMR spectra. Each conformation is itself composed of many subconformations in rapid equilibrium. Partially...

Collisions of I2 in the E electronic state with rare gas atoms result in electronic energy transfer to the D, beta, and D' ion-pair electronic states. Rate constants for each of these channels have been measured when I2 is initially prepared in the J = 55, nu = 1 and 2 levels in the E state. The rate constants and effective hard sphere collision cross sections confirm the trends observed when n...

We present a rigorous quantum study of spin-exchange transitions in collisions of the alkali-metal atoms with He in the presence of an external magnetic field. Using accurate ab initio interaction potentials, we obtain refined estimates for the Fermi contact interaction constants for complexes of Na, K, and Rb atoms with He. Ab initio calculations show that the Fermi contact interaction in Li-H...

A hybrid mesoscopic multiparticle collision model is used to study diffusion-influenced reaction kinetics. The mesoscopic particle dynamics conserves mass, momentum, and energy so that hydrodynamic effects are fully taken into account. Reactive and nonreactive interactions with catalytic solute particles are described by full molecular dynamics. Results are presented for large-scale, three-dime...

The ion-pair states of molecular iodine provide a unique system for studying the efficiency, selectivity, and mechanisms of collision-induced non-adiabatic transitions. Non-adiabatic transitions between the first-tier ion-pair states in collisions with molecular partners and rare gases are analyzed and discussed. The qualitative features of the rate constants and product state distributions und...

The thermodynamics and kinetics of the interaction of dihydrofolate reductase (DHFR) with methotrexate have been studied by using fluorescence, stopped-flow, and single-molecule methods. DHFR was modified to permit the covalent addition of a fluorescent molecule, Alexa 488, and a biotin at the N terminus of the molecule. The fluorescent molecule was placed on a protein loop that closes over met...

Accurate measurements of longitudinal relaxation time constants (T1) in solid-state nuclear magnetic resonance (SSNMR) experiments are important for the study molecular-level structure and dynamics. Such often made under magic-angle spinning conditions; however, there numerous instances where they must be on stationary samples, which give rise to broad powder patterns arising from large anisotr...

Free-radical polymerization of styrene conducted in a spinning disc reactor (SDR) results significant increases conversion one pass, equivalent to few seconds residence time, with little change the number average and weight molecular weights polydispersity compared SDR feed pre-polymerized batch reactor. Results our experimental studies are presented this paper rationale, based on simulation st...