in this research at the first, captopril drug (ca) and its fullerene connected form (fca) wereoptimized. natural bond orbital (nbo) calculations for these compounds were carried out at theb3lyp/6-31g quantum chemistry level, in the gas phase and the liquid phase. these calculations canbe performed at different accuracy levels depending on the aim of the theoretical study [1]. forinstance, densi...

Atomic structures, energies, and stress distributions of symmetrical ^011& tilt grain boundaries ~GB’s! and selected GB triple junctions ~TJ’s! in diamond as well as a multiply twinned diamond particle have been calculated using an analytic bond order potential function. In general, energies of ^011& tilt GB’s are about 1 J/m lower than those for ^001& tilt GB’s calculated with the same analyti...

statement of problem: the achievement of a good and durable dentin/composite resin bond is an important task in restorative dentistry. the application of acid conditioners and dentin bonding agents is an accepted method to enhance this bond strength. pretreating of dentin surface by laser irradiation seems to be a supplemental way to obtain better results, since lased dentin is more roughened a...

Intramolecular interactions of the functional groups, carboxylic acid, amino, and phenyl in L-phenylalanine have been revealed through inner shell chemical shift. The chemical shift and electronic structures are studied using its derivatives, 2-phenethylamine (PEA) and 3-phenylpropionic acid (PPA), through substitutions of the functional groups on the chiral carbon C(alpha), i.e., carboxylic ac...

Introduction Nitrogen, like many other chemical elements, has catenation ability. The variety and multiplicity of molecular structures with nitrogen-nitrogen bond is significantly smaller than for carbon. Such compounds are of particular interest as potential high-energy density materials (HEDM) [1], because they can undergo exothermic reaction Nx → (x/2)N2 releasing 50 kcal/mol or more per one...

A new method for refinement of 3D molecular structures by geometry optimization is presented. Prerequisites are a force field and a very fast procedure for the calculation of chemical shifts in every step of optimization. To the energy, provided by the force field (COSMOS force field), a pseudoenergy, depending on the difference between experimental and calculated chemical shifts, is added. In ...

All chemical transformations pass through an unstable structure called the transition state, which is poised between the chemical structures of the substrates and products. The transi‐ tion states for chemical reactions are proposed to have lifetimes near 10-13 sec, the time for a single bond vibration. Thus, the transition state is the critical configuration of a reaction sys‐ tem situated at ...

The main objective of this Account is to assess the challenges of transmission electron microscopy (TEM) of molecules, based on over 15 years of our work in this field, and to outline the opportunities in studying chemical reactions under the electron beam (e-beam). During TEM imaging of an individual molecule adsorbed on an atomically thin substrate, such as graphene or a carbon nanotube, the ...