Introduction:In an ideal parallel-hole collimator, thickness of septal material should be sufficient to stop more than 95% of incident photons. However, some photons pass the septa without interaction or experience scattering before they reach the detector. In this study, we determined different contribution of collimator responses consist of geometrical response, septal penetr...

The activation strain or distortion/interaction model is a tool to analyze activation barriers that determine reaction rates. For bimolecular reactions, the activation energies are the sum of the energies to distort the reactants into geometries they have in transition states plus the interaction energies between the two distorted molecules. The energy required to distort the molecules is calle...

We report variational and diffusion quantum Monte Carlo ground-state energies of the three-dimensional electron gas using a model periodic Coulomb interaction and backflow corrections for N = 54, 102, 178, and 226 electrons. We remove finite-size effects by extrapolation and we find lower energies than previously reported. Using the Hellman-Feynman operator sampling method introduced in Gaudoin...

Interaction energies between substitutional 3d transition metal elements and an interstitial carbon atom in iron are estimated using the first-principles calculation. Calculated interaction energies are in good agreement with the experimental values reported for Co, Ni and Cu, showing a repulsive interaction experimentally. However, the interaction for such elements as Ti, V, Cr and Mn are also...

We investigate nonlocal-interaction energies on the space of probability measures. We establish sharp conditions for the existence of minimizers for a broad class of nonlocalinteraction energies. The condition is closely related to the notion of H-stability of pairwise interaction potentials in statistical mechanics. Our approach uses the direct method of calculus of variations.

We extend density-matrix expansions in nuclei to higher orders in derivatives of densities and test their convergence properties. The expansions allow for converting the interaction energies characteristic to finite- and short-range nuclear effective forces into quasilocal density functionals. We also propose a new type of expansion that has excellent convergence properties when benchmarked aga...

We contrast the interaction of mercury with adsorbed orthocarborane films and semiconducting (dehydrogenated) boron carbide. Photoemission spectra reveal small shifts in orthocarborane (C2B10H12) molecular orbital binding energies as well as the shift in mercury 5d5/2 shallow core level binding energies, suggesting only small interaction between mercury and the molecular film. Mercury does, how...

accurate quantum chemical computations based on density functional theory (dft) were performed on the series of 2-(4-(naphthalen-2-yl)-1,2,3-thiadiazol-5-ylthio)-n-acetamide (tta) derivatives. the local reactivity of the acetamide derivatives as anti-hiv drugs were studied in terms of fukui functions in the framework of dft. the results based on the basis set superposition error (bsse) correcti...

to get a mole of a gas, it is necessary to calculate the intermolecular interaction. theseintermolecular interactions can be depicted by drawing the potential energy of a pair molecule inrelation to the distance. the intermolecular potential energy surface in the mixtures of ch4-h2cogases from ab initio calculations has been explored. in ab initio calculations the basis setsuperposition error (...

The Density Functional Theory (DFT) and the Natural Bond Orbital (NBO) calculations basedmethod B3LYP/6-31G* were carried out to study the interaction of carbon nanotube (8,0) withnitrobenzene in two situations perpendicular and parallel. Formation energies of compounds,charges, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular'orbital (LUMO) and the HOMO-LUMO ba...