The molecular structure of closo-9,12-(SH)2-1,2-C2B10H10 has been determined by the concerted use of quantum chemical calculations and gas electron diffraction (GED). For the purposes of GED, the architecture of the carbaborane cage was simplified to allow it to have C2v symmetry, while the positioning of the thiol groups means that the molecule had overall C1 symmetry. The accuracy of the expe...

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 ...

The development of new technologies has an impact on a better understanding of the components present in inter/circum-stellar space and also of the interactions of different species.[1] That is one of Astrochemistry focus, and it is a challenge for the scientists, even more due to the limited access and knowledge on that characteristic environment. [2,3] Therefore, the study of interactions bet...

We report here a benchmark study on the bimolecular nucleophilic substitution (S(N)2) reaction between hydride and methane, for which we have obtained reference energies at the coupled cluster toward full configuration-interaction limit (CC-cf/CBS). Several wavefunction (HF, MP2, coupled cluster) and density functional methods are compared for their reliability regarding these reference data.

A theoretical study of interaction of ethylene with Cuz is considered using SCF/CASSCF/MP2 methods. The calculated dissociation energy is in good agreement with available experimental data. Our studies reveal that the perpendicular approach of Cu2 is more favored than the parallel approach. The strong bonding is assisted through the donation of x-electronic density from ethylene to the 4p orbit...

We propose to construct electron correlation methods that are scalable in both molecule size and aggregated parallel computational power, in the sense that the total elapsed time of a calculation becomes nearly independent of the molecular size when the number of processors grows linearly with the molecular size. This is shown to be possible by exploiting a combination of local approximations a...

Aromatic amino acid residues are often present in carbohydrate-binding sites of proteins. These binding sites are characterized by a placement of a carbohydrate moiety in a stacking orientation to an aromatic ring. This arrangement is an example of CH/pi interactions. Ab initio interaction energies for 20 carbohydrate-aromatic complexes taken from 6 selected ultra-high resolution X-ray structur...

We present a reduced scaling and exact reformulation of state specific complete active space second-order perturbation (CASPT2) analytical gradients in terms the MP2 Fock derivatives using supporting subspace method. This work follows naturally from formulation CASPT2 energy dressed orbitals builds. For given configuration, corresponding to MP2-gradient can be evaluated with O(N5) operations, w...

Given the agreement among TCSCF, MP2, and MRMP methods, it is concluded that the structure of Si9H12 is symmetric, that dynamic correlation does not play a major role in determining the structure, and that DFT incorrectly predicts Si9H12 to be buckled.