The direct ~recomputation of two-electron integrals! implementation of the gauge-including atomic orbital ~GIAO! and the CSGT ~continuous set of gauge transformations! methods for calculating nuclear magnetic shielding tensors at both the Hartree-Fock and density functional levels of theory are presented. Isotropic C, N, and O magnetic shielding constants for several molecules, including taxol ...

The 1H NMR spectra of 1-halonaphthalenes were recorded and assigned. These data together with the known 1H chemical shifts of the halobenzenes and of H-5 in 4-halophenanthrenes were used to investigate different models of halogen SCS using the CHARGE program. Good agreement was obtained with the observed shifts for the fluoro compounds, but a new model which included the anisotropy of the C-X b...

The protocol of privacy-preserving clustering with distributed EM mixture modeling was proposed. However, it is not completely secure in the situation that something more than just the model parameters are revealed. Specially, when the dataset is horizontally partitioned into just two parts, this reveals extra information. The aim of this work is firstly to develop a more general protocol which...

The change in (1)H NMR chemical shifts upon hydrogen bonding was investigated using both experimental and theoretical methods. The (1)H NMR spectra of a number of phenols were recorded in CDCl(3) and DMSO solvents. For phenol, 2- and 4-cyanophenol and 2-nitrophenol the OH chemical shifts were measured as a function of concentration in CDCl(3). The plots were all linear with concentration, the g...

Twenty one conformationally fixed amines and their N,N-dimethyl derivatives were obtained commercially or synthesized. These included cis and trans 4-t-butyl cyclohexylamine, 2-exo and 2-endo norbornylamine, 2-adamantylamine, 4-phenylpiperidine, 1-napthylamine and tetrahydro-1-napthylamine. The (1)H NMR spectra of these amines were measured in CDCl(3) solution, assigned and the (1)H chemical sh...

A series of monocyclic planar inorganic compounds have been optimized at the B3LYP/6-311+G* level. GIAO-B3LYP nucleus-independent chemical shifts (NICS) profiles calculated in the perpendicular direction of each ring show that the series of analyzed compounds can be classified in three groups according to their aromatic, non-aromatic or antiaromatic character. Our results suggest exercising cau...

The fluxional barrier of (dicarbonyl)[dihydrobis(3,5-dimethylpyrazol-1-yl)borato][eta-(1,2,3)-2-methylpropen-1-yl]-molybdenum (1) has been measured and a complete assignment of its (1)H, (13)C and (15)N NMR signals has been carried out. Theoretical calculations at the B3LYP/LANL2DZ level including GIAO absolute shieldings (sigma) have allowed to analyze the molecular contributions to the barrie...

A series of oxonium and carboxonium ions and their corresponding protonated dications were investigated by ab initio/IGLO/GIAO-MP2 methods. The calculated 17O and 13C NMR chemical shifts were compared with the solution phase experimental data for the monocations. The structures and energies of a number of oxonium and carboxonium dications and the effect of diprotonation on the 17O and 13C NMR c...

Văn xuôi Ngọc Giao đã tái hiện một hình ảnh làng quê vừa truyền thống pha chút đại, êm đềm xao động, đáng yêu, sống sợ, phải đổi thay. Tuy nhiên, đây vẫn là vấn đề chưa được nghiên cứu tìm hiểu thấu đáo. Qua khảo sát, kê, phân tích, so sánh về trong văn Giao, chúng tôi bước đầu nhận thấy: Đó yên bình, nặng nghĩa tình nhưng nghèo đói, bế tắc; Làng tiêu điều, đau thương vùng giặc chiếm đóng và dầ...

nowadays nmr spectroscopy becomes a powerful tool in chemistry because of the nmr chemical shifts. hartree–fock theory and the gauge-including atomic orbital (giao) methods are used in the calculation of 29si nmr chemical shifts of various silicate species in the silicate solution as initial components for zeolite synthesis both in gas and solution phase. calculations have been performed at geo...