Abstract Betahistine serves as a medicament widely used in curing some diseases related to the nervous system. Its molecular properties have been studied by ab initio MO-LCAO-SCF method followed correction electron correlation (MP2) vacuo well water solvent. The chemical potential (electronegativity) and hardness were verified valuable descriptors compared with structurally analogous species.

Structures, vibrational frequencies, and energies for the chlorinated disilenes, their dibridged isomers, and the transition states connecting the chlorinated disilenes to the corresponding silylsilylenes are presented. Geometries and frequencies were obtained at the MP2/6-31G(d,p) level, and energetics were calculated at the G2, G2(MP2), MP4/6-31+G(2df,p), and/or MP2/6-31+G(2df,p) levels of th...

A simple modification of the zeroth-order regular approximation (ZORA) in relativistic theory is suggested to suppress its erroneous gauge dependence to a high level of approximation. The method, coined gauge-independent ZORA (ZORA-GI), can be easily installed in any existing nonrelativistic quantum chemical package by programming simple one-electron matrix elements for the quasirelativistic Ha...

The development of Møller–Plesset perturbation theory (MPPT) has seen four different periods in almost 80 years. In the first 40 years (period 1), MPPT was largely ignored because the focus of quantum chemists was on variational methods. After the development of many-body perturbation theory by theoretical physicists in the 1950s and 1960s, a second 20-year long period started, during which MPn...

The thermal (E)/(Z)-isomerization of 3-methyl-4-pyrimidinimine, 3MePMI, has been studied in the gas phase at MP2/6-31G* and with the inclusion of medium effects using the polarizable continuum method, PCM(MP2/6-31G*), and the solvation model density method, SMD(MP2/6-31G*). For the free molecule and for 3MePMI in each of 14 solvents, the structures were determined of the (E)- and (Z)-isomers, o...

Stimulated by its success in both bioconjugation and surface modification, we studied the strain-promoted oxidation-controlled cycloalkyne-1,2-quinone cycloaddition (SPOCQ) in three ways. First, the second-order rate constants and activation parameters (ΔH⧧) were determined of various cyclooctynes reacting with 4-tert-butyl-1,2-quinone in a SPOCQ reaction, yielding values for ΔH⧧ of 4.5, 7.3, a...

The surgical evaluation of haemorrhagic infarcted intestine and the decision for or against bowel resection require a lot of experience and are subjective. The aim of this prospective, clinical study was to examine the correlation between oxygen saturation and small intestinal wall (IW) thickness, using two objective methods. In 22 colicky horses, the blood flow, oxygen saturation and relative ...

Electron attachment and detachment kinetics of 2-C(4)F(8) were studied over the temperature range 298-487 K with a flowing-afterglow Langmuir-probe apparatus. Only parent anions were formed in the attachment process throughout this temperature range. At the highest temperatures, thermal electron detachment of the parent anions is important. Analysis of the 2-C(4)F(8) gas showed an 82/18 mixture...

On the basis of the fragment molecular orbital (FMO) method, we performed the FMO-MP2 and FMO-MP3 electronic-state calculations on the Earth Simulator (ES2) for a protein complex consisting of HA (hemagglutinin) trimer and two Fab fragments and a complex of NA (neuraminidase) and oseltamivir inhibitor of influenza virus. The FMO-MP2/6-31G jobs were completed in 0.8 hours for the HA monomer and ...

Human immunodeficiency virus type 1 encapsidates two copies of viral genomic RNA in the form of a dimer. The dimerization process initiates via a 6-nucleotide palindrome that constitutes the loop of a viral RNA stem-loop structure (i.e., stem loop 1 [SL1], also termed the dimerization initiation site [DIS]) located within the 5' untranslated region of the viral genome. We have now shown that de...