In this article, we present a fragment model potential approach for the description of the crystalline environment as an extension of the use of embedding ab initio model potentials (AIMPs). The biggest limitation of the embedding AIMP method is the spherical nature of its model potentials. This poses problems as soon as the method is applied to crystals containing strongly covalently bonded st...

The diffusion Monte Carlo (DMC) method is applied to compute the ground state energies of the water monomer and dimer and their D2O isotopomers using MB-pol; the most recent and most accurate ab inito-based potential energy surface (PES). MB-pol has already demonstrated excellent agreement with high level electronic structure data, as well as agreement with some experimental, spectroscopic, and...

Trends in the growth of extended interstitial defects are extracted from extensive tight-binding and ab inito local density approximation simulations. With an increasing number of interstitials, the stable defect shape evolves from compact to chainlike to rodlike. The rodlike 311 defect, formed from (011) interstitial chains, is stabilized as it grows, elongating in the chain direction. Accurat...

The activation energy to reaction is a key quantity that controls catalytic activity. Having used ab inito calculations to determine an extensive and broad ranging set of activation energies and enthalpy changes for surface-catalyzed reactions, we show that linear relationships exist between dissociation activation energies and enthalpy changes. Known in the literature as empirical Brønsted-Eva...

The reliability of four force fields developed for 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids are compared to an ab inito molecular dynamics simulation regarding structural properties. Except the hydrogen bond structure between the most acidic hydrogen atom of the imidazolium ring and the nitrogen atom of the anion as well as the intramolecular potential surface...

We report a numerical investigation on the catalytic growth mechanism of a single-walled carbon nanotube (SWNT) inside a template SWNT, that is, formation of a double-walled carbon nanotube (DWNT). The molecular dynamics simulations together with complementary ab inito calculations suggest that the DWNT formation from thermally annealed metallocene-encapsulating SWNT goes through formation of m...

Quaternisation of 3,5-diaryl-1,2,4-thiadiazoles with trimethylsilylmethyl triflate at 40 8C occurred at N-2. Separate desilylation of the salts resulted in a ring expansion to substituted 2H-1,3,5-thiadiazines 5. Heating of these with ethanolic sodium ethoxide caused sulfur extrusion and ring contraction to 2,4-disubstituted imidazoles 6. 3,4-Diaryl1,2,5-thiadiazoles were less reactive to alkyl...

The H nuclear quadrupole interaction parameters, 2 and , are closely related to the shape of the potential energy surface at hydrogen bonds and depend sensitively on their geometry. We measured the temperature dependence of the H NMR spectra of the crystalline acidic salts KDCO3, KD acetylenedicarboxylate, RbD acetylenedicarboxylate, and KD maleate, which contain very short O-D O type hydrogen ...

The search for an accurate and efficient protein conformation predicting method started around 1972 with a theoretical study on the ribonuclease folding. Surprisingly, physicist, chemists, and mathematicians have only been making very minute progress towards the empirical prediction algorithm of three-dimensional protein folding structures. The three most commonly accepted methods used in the p...

In this study we investigate the effect of atoms such as B, N, Ge and Sn on the optical and the electrical properties of capped (5, 0) zigzag carbon nanotube, using DFT calculation method. These elements were attached to the one end of the carbon nanotube. We considered four different structure designs as possible candidates for a p-n junction device. The electrical properties of these structur...