The atomic orbital basis set limit is approached in periodic correlated calculations for solid LiH. The valence correlation energy is evaluated at the level of the local periodic second order Møller-Plesset perturbation theory (MP2), using basis sets of progressively increasing size, and also employing "bond"-centered basis functions in addition to the standard atom-centered ones. Extended basi...

BACKGROUND 2-amino pyridine derivatives have attracted considerable interest because they are useful precursors for the synthesis of a variety of heterocyclic compounds possessing a medicinal value. In this work we aim to study both structural and electronic as well as high quality vibrational spectra for 2-amino-3-methylpyridine (2A3MP) and 2-amino-4-methylpyridine (2A4MP). RESULTS Møller-Pl...

ab initio calculations at the density functional theory (dft) and the second-order møller−plessetperturbation theory levels with 6-31+g(d), 6-31g(d) basis sets for non-metal atoms and lanl2dzfor metal have been performed for the adsorption of dimethyl methylphosphonate (dmmp) on znoby gaussisn 98 program. the calculated rotational constants by b3lyp/6-31g(d) are in moreagreement with the experi...

MP2 provides a good description of hydrogen bonding in water clusters and includes longrange dispersion interactions without the need to introduce empirical elements in the description of the interatomic potential. To assess its performance for bulk liquid water under ambient conditions, an isobaric-isothermal (NpT) Monte Carlo simulation at the second-order Moller-Plesset perturbation theory l...

The alkylation of benzene by ethene over H-ZSM-5 is analyzed by means of a hybrid MP2:DFT scheme. Density functional calculations applying periodic boundary conditions (PBE functional) are combined with MP2 energy calculations on a series of cluster models of increasing size which allows extrapolation to the periodic MP2 limit. Basis set truncation errors are estimated by extrapolation of the M...

For many years, researchers have been developing theoretical methods of estimating reaction rates and energetics when experimental measurements are not available. Recent advances have led to composite energy methods with near chemical accuracy. The performance of these new methods for predicting activation energies and rate constants have not been evaluated for large hydrocarbon cracking reacti...

The prediction of 13C chemical shifts can be challenging with density functional theory (DFT). In this study 39 different functionals and three basis sets were tested on neutral alkylpyrroles their corresponding protonated species. calculated shielding constants compared to experimental data results from previous calculations at the MP2. We find that meta-hybrid TPSSh either Pople style set 6-3...

the use of appropriate level of theories for studying weak van der waal interactions such as 8-8stacking interactions of aromatic molecules has been an important aspect, since the high levelmethods have limitations for application to large molecules. the differences in the stacking energiesof various aromatic molecular structures are found significant. it is also very important for identifyingt...

BACKGROUND The Drosophila central nervous system (CNS) develops from a segmentally reiterated array of 30 neural precursors. Each precursor acquires a unique identity and goes through a stereotyped cell lineage to produce an invariant family of neurons and/or glia. The proneural genes achaete, scute and lethal of scute are required for neural precursor formation in the Drosophila CNS, and are e...