Hartree-Fock and density functional theory studies on ionization and fragmentation of halomethane molecules by positron impact

Size dependent structural, electronic, and magnetic properties of Sc(N) (N=2-14) clusters investigated by density functional theory

Structural, electronic, and magnetic properties of ScN (N=2-14) clusters have been investigated using density functional theory (DFT) calculations. Different spin states isomer for each cluster size has been optimized with symmetry relaxation. The structural stability, dissociation energy, binding energy, spin stability, vertical ionization energy, electron affinity, chemical hardness, and size dependent magnetic moment per atom are calculated for the energetically most stable spin isomer for each size. The structural stability for a specific size cluster has been explained in terms of atomic shell closing effect, close packed symmetric structure, and chemical bonding. Spin stability of each cluster size is determined by calculating the value of spin gaps. The maximum value for second-order energy difference is observed for the clusters of size N = 2, 6, 11, and 13, which implies that these clusters are relatively more stable. The magnetic moment per atom corresponding to lowest energy structure has also been calculated. The magnetic moment per atom corresponding to lowest energy structures has been calculated. The calculated values of magnetic moment per atom vary in an oscillatory fashion with cluster size. The calculated results are compared with the available experimental data.

Monte Carlo Simulation of Equilibrium Reactions at Vapor−Liquid Interfaces

Chemical reactions are known to behave differently, depending upon their local environment. While the interactions with neighboring molecules may alter both the kinetics of chemical reactions and the overall equilibrium conversion, we have performed simulations of the latter. The particular environment that we address is the vapor-liquid interface, since only a few, limited studies have explored the influence of an interface on equilibrium reaction behavior. Simple dimerization reactions are modeled, as well as more complex multicomponent reactions, using the reactive Monte Carlo (RxMC) simulation technique. We find that the conversion of a reaction can be markedly different at an interface as compared to the bulk vapor and liquid phases, and these trends are analyzed with respect to specific intermolecular interactions. In conjunction, we calculate the surface tension of the reacting fluids at the interface, which is found to have unusual scaling behavior, with respect to the system temperature.