In this work, we present a survey of the different parallel programming models and tools available today with special consideration to their suitability for high-performance computing. Thus, review shared distributed memory approaches, as well current heterogeneous model. addition, analyze how partitioned global address space (PGAS) hybrid are used combine advantages systems. The work is completed by considering languages specific support paradigm. all cases, characteristics, strengths,...

This work presents a theoretical study of acetohydroxamic acid and its protonation processes using ab initio methodology at the MP2(FC)/cc-pdVZ level. We find amide form more stable than imidic tautomer by less 1.0 kcal mol(-)(1). For comparison with experimental data, three-dimensional conformational is performed on most (amide). From this study, different barriers to rotation inversion are determined intramolecular hydrogen bond between OH group carbonyl oxygen characterized. The...

Theoretical (ab initio calculations) and experimental (NMR, spectrophotometric, potentiometric measurements) investigations of the isomers acetohydroxamic acid (AHA) their deprotonation processes have been performed. Calculations with Gaussian 98 package, refined at MP2(FC)/AUG-cc-pVDZ level considering molecule isolated, indicate that Z(cis) amide is most stable form neutral molecule. This species less (Z)-imide undergo deprotonation, giving rise to two anions. Upon E(trans) forms give...

ADVERTISEMENT RETURN TO ISSUEArticleNEXTWagging and torsion vibronic structure in the T1 .rarw. S0 electronic spectrum of acetaldehydeAlfonso Nino, Camelia Munoz-Caro, David C. MouleCite this: J. Phys. Chem. 1994, 98, 6, 1519–1524Publication Date (Print):February 1, 1994Publication History Published online1 May 2002Published inissue 1 February 1994https://doi.org/10.1021/j100057a001RIGHTS & PERMISSIONSArticle Views63Altmetric-Citations37LEARN ABOUT THESE METRICSArticle Views are...

A study of the effect anharmonicities and large amplitude vibrations on thermodynamic properties water dimer is presented. Different vibrational models have been constructed using ab initio data obtained at MP2(Full)/6-311++G(2d,2p) level. In particular, we present first complete analysis rotation hydrogen donor monomer around O···O axis. The potential barrier was found to be 221 cm-1. variational calculation torsional energy levels yields a fundamental frequency 105 stretching mode...

A theoretical and experimental study on the structure deprotonation of benzohydroxamic acid (BHA) has been performed. Calculations at RHF/cc-pVDZ level, refined by B3LYP/AUG-cc-pVDZ method, indicate that, in gas phase, Z amide is most stable both neutral deprotonated BHA. (1)H-(1)H nuclear Overhauser enhancement spectroscopy correlation spectra acetone, interpreted with ab initio interatomic distances, reveal that BHA split into E forms, [E]/[Z] ratio being 75:25 -80 degrees C. The formation...

This work presents a theoretical mechanistic study of the protonation pyridine in water clusters, at B3LYP/cc-pVDZ theory level. Clusters from one to five molecules were used. Starting previously determined structures, reaction paths for process identified. For complexes with clusters up three just transition state (TS) links solvated and protonated forms. It is found that activation energy decreases number molecules. four two states are found. molecules, first TS starting structure new,...

The structural and spectroscopic effects of hydrogen bonding on isolated 2,2,2-trifluoroethanol (TFE) its molecular complexes are theoretically investigated at the MP2/aug-cc-pVDZ level. As a result, previous interpretations relative stability trans gauche conformers molecule revised. We show that prevalence form is due to decrease repulsion forces, rather than formation an intramolecular bond. find instability geometry caused by forces between oxygen electronic pair fluorine atom clouds,...

The laser induced T1(nπ*)←S0 phosphorescence excitation spectrum of jet-cooled acetaldehyde has been observed for the first time with a rotating slit nozzle system. vibronic origins were fitted to set levels that obtained from Hamiltonian employed flexible torsion-wagging large amplitude coordinates. potential surface extracted fitting procedure yielded barriers torsion and inversion 609.68 869.02 cm−1, respectively. Minima in hypersurface at θ=61.7° α=42.2° defined equilibrium positions...

The protonation of pyridine in water clusters as a function the number molecules was theoretically analyzed prototypical case for organic bases. We determined variation structural, bonding, and energetic properties on protonation, well stabilization ionic species formed. Thus, we used supermolecular models which interacts with up to five molecules. For each complex, most stable unprotonated protonated structures from simulated annealing at semi ab initio level. were optimized B3LYP/cc-pVDZ...

Abstract This work presents an analysis of the equivalence MP2 and DFT (B3LYP functional) conformational populations. As a test case, we select three cholinergic agents ( trans ‐nicotine, acetylcholine, nicotinic analgesic ABT‐594), where minima on energy hypersurfaces expand large range energies (∼0–30 kJ mol −1 ). From energetic structural data obtained in vacuo at B3LYP/cc‐pVDZ levels, build partition functions, including effect kinetic rotovibrational coupling. Our results physiological...