نتایج جستجو برای: covalent bond

تعداد نتایج: 85898  

Journal: :Physical chemistry chemical physics : PCCP 2011
Andrew Das Arulsamy Zlatko Kregar Kristina Eleršič Martina Modic Uma Shankar Subramani

Hydrogen produced from the photocatalytic splitting of water is one of the reliable alternatives to replace the polluting fossil and the radioactive nuclear fuels. Here, we provide unequivocal evidence for the existence of blue- and red-shifting O-H covalent bonds within a single water molecule adsorbed on the MgO surface as a result of asymmetric displacement polarizabilities. The adsorbed H-O...

2017
Yanan Tang Hongwei Zhang Zigang Shen Mingyu Zhao Yi Li Xianqi Dai

We use first-principles calculations to investigate the geometric, electronic and magnetic properties of metal adatoms on two typical graphene substrates (monolayer and bilayer). Firstly, we study the adsorption behaviors and the doping effects of metal atoms on pristine and defective bilayer graphene sheets (PBG and DBG). It is found that the metal doping in DBG sheets is more stable than that...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1972
D V Santi C S McHenry

5-Fluoro-2'-deoxyuridylate causes a rapid inactivation of thymidylate synthetase that is dependent upon prior complexation of the cofactor 5,10-methylenetetrahydrofolate. The enzyme-5-fluoro-2'-deoxyuridylate complex may be isolated on nitrocellulose membranes and is not disrupted by 6 M urea. Upon reaction of 5-fluoro-2'-deoxyuridylate with the enzyme in the presence of 5,10-methylenetetrahydr...

2011
Huan-Huan Wang Qian Gao Yue Cui Lin Wang Ya-Bo Xie

The title tetra-nuclear complex, [Au(4)(C(25)H(21)P(2))Cl(3)(C(25)H(22)P(2))]·2C(4)H(8)O, features two non-equivalent Ph(2)PCPPh(2) fragments, one of which represents the 'complete' mol-ecule (with two H atoms at the central C atom); each of the two P atoms of this mol-ecule is coordinated by an Au atom [Au-P = 2.2256 (13) and 2.2710 (13) Å], and these two Au atoms form an Au-Au bond [3.2945 (3...

Journal: :The Journal of chemical physics 2008
Daniel R Rohr Katarzyna Pernal Oleg V Gritsenko Evert Jan Baerends

A recently proposed series of corrections to the earliest JK-only functionals has considerably improved the prospects of density matrix functional theory (DMFT). Still, the most advanced of these functionals (correction C3) requires a preselection of the terms in the pair density Gamma(r(1),r(2)) involving the bonding and antibonding natural orbitals (NOs) belonging to an electron pair bond. Id...

2009
Xiu-Zhu Lin Jing Li Qi-Hui Wu

The adsorption of a single Ag atom on both clear Si(111)-7 × 7 and 19 hydrogen terminated Si(111)-7 × 7 (hereafter referred as 19H-Si(111)-7 × 7) surfaces has been investigated using first-principles calculations. The results indicated that the pre-adsorbed H on Si surface altered the surface electronic properties of Si and influenced the adsorption properties of Ag atom on the H terminated Si ...

Journal: :Physical review letters 2011
A Gerlach T Hosokai S Duhm S Kera O T Hofmann E Zojer J Zegenhagen F Schreiber

In order to investigate the orientational ordering of molecular dipoles and the associated electronic properties, we studied the adsorption of chlorogallium phthalocyanine molecules (GaClPc, Pc=C32N8H16(-2) on Cu(111) by using the x-ray standing wave technique, photoelectron spectroscopy, and quantum mechanical calculations. We find that for submonolayer coverages on Cu(111) the majority of GaC...

Journal: :Physical chemistry chemical physics : PCCP 2014
Ralf Tonner Nicola Gaston

We consider the structural similarity of small gallium clusters to the bulk structure of α-gallium, which has been previously described as a molecular metal, via density functional theory-based computations. Previous calculations have shown that the tetramer, the hexamer, and the octamer of gallium are all structurally similar to the α-phase. We perform an analysis of the bonding in these clust...

2014
Tomoko Sekine Takahiro Kakuta Takashi Nakamura Yuichiro Kobayashi Yoshinori Takashima Akira Harada

Cross-coupling reactions are important to form C-C covalent bonds using metal catalysts. Although many different cross-coupling reactions have been developed and applied to synthesize complex molecules or polymers (macromolecules), if cross-coupling reactions are realized in the macroscopic real world, the scope of materials should be dramatically broadened. Here, Suzuki-Miyaura coupling reacti...

Journal: :Physical review letters 2012
J T Okada P H-L Sit Y Watanabe Y J Wang B Barbiellini T Ishikawa M Itou Y Sakurai A Bansil R Ishikawa M Hamaishi T Masaki P-F Paradis K Kimura S Nanao

Metallic liquid silicon at 1787 K is investigated using x-ray Compton scattering. An excellent agreement is found between the measurements and the corresponding Car-Parrinello molecular dynamics simulations. Our results show persistence of covalent bonding in liquid silicon and provide support for the occurrence of theoretically predicted liquid-liquid phase transition in supercooled liquid sta...

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