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1

The Cooperativity of C–H···F Blue-Shifting Hydrogen Bonds. Static and Dynamic Calculations on CF3H Dimer, Trimer and Tetramer

Rodziewicz P., Rutkowski K. S., Melikova S. M.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 5

1075-1084

EN

Static and dynamic density functional theory calculations on CF3H dimer, trimer and tetramer are presented. All the structures analyzed present the cyclic C–H···F pattern. The energetic, geometrical and vibrational contributions resulting from cooperative effects have been analyzed. The Car-Parrinello molecular dynamics technique has been used to estimate the cooperative effects temperature dependence. The results of simulations might support future molecular beam or supersonic jet experimental studies.

2

On Adsorption of Hydrogen on (100) Titanium Hydride Surface

Gryciuk M., Górecki J.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 10

1981-1990

EN

We apply quantum density functional theory methods to calculate the reaction path linking a free hydrogen molecule placed over TiH2 (100) surface with a pair of hyrogen atoms ad sorbed on it. The considered path is composed of highly symmetrical orientations of H2 molecule; in the process of dissociative adsorption the line linking hydrogen atoms is al ways parallel to the surface and located on the symmetry plane of the supercell. The results indicate that adsorption is characterized by the energetic barrier (1.18 eV/molecule) and the reaction heat (0.26 eV/ atom).

3

Atomic modelling of point defects in B2-RuAl

Sot R., Kurzydlowski K. J.

Materials Science Poland

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2005

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Vol. 23, No. 2

407--411

EN

Ab initio calculations based on density functional theory (DFT) and the pseudopotential method have been used to study B2-structured RuAl. The structural parameters, volume changes of single defects and pressure caused by the presence of point defects in B2-RuAl intermetallic compound were computed by the ab initio pseudopotential method with the plane-wave basis set and a generalized gradient approximation (GGA). The calculated structural parameters are in good agreement with available experimental data.

4

On hydrogen Layers on the (100)Titanium Hydride Surface

Gryciuk M., Górecki J.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 7

993-999

EN

Electronic structure calculations based on the density functional theory (DFT) have been applied to the adsorption of hydrogen on the (100) plane of TiH2. Calculations have been performed for a supercell of TiH2 and the periodic boundary conditions have been used. Three different monolayers, two double layers and one selected submonolayer of hydrogen have been considered. It is shown that the most dense coverage corresponds to a submonolayer composed of atoms in the bridge position with respect to titanium atoms on the surface. Both, binding energy and the hydrogen density on the surface agree with the experimental results.

5

Density Functional Theory Calculations of Adsorption of Hydrogen on the (100) Titanium Hydride Surface

Gryciuk M., Górecki J.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 1

123-128

EN

Electronic structure calculations based on the density functional theory (DFT) have been applied to the adsorption of hydrogen on the (100) plane of TiH2. Calculations are performed for a single hydrogen atom placed over a supercell of TiH2 and the periodic boundary conditions are used, so effectively such system describes a submonolayer coverage. The total energy have been calculated for three different positions of hydrogen over the TiH2 supercell. The results based on the local density approximation (LDA) and the generalized gradient approximation (GGA) are compared.

6

Molecular orbital study of hydrated clusters of LiOH

Miyazaki S., Osamura Y.

Bulletin of the Polish Academy of Sciences. Chemistry

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2002

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Vol. 50, No. 4

463-489

EN

The molecular structures of the hydrated species of LiOH, LiOH(H2O)n for n = 1 ~ 5, were studied in terms of density functional B3LYP molecular orbital method. Since the water molecules act as both acid and base toward LiOH, all stable structures located at energy minima are found to be cyclic geometries. The distance between Li+ and OH(-) increases as the number of water molecules increase. Due to the covalent nature of LiOH, the dissociation of LiOH toward Li and OH(-) requires sufficient number of water molecules. Only non-dissociated structures were obtained in the case of a small number of water molecules (n < 3). Even in the case of LiOH(H(2)O)(5), the non-dissociated structures are calculated to be more stable than the dissociated structures. The number of isomers increases substantially with the increase of the number of water molecules. The ionic structures can be classified into contact ion-pair and solvent separated ion-pair structures. The four water molecules can coordinate to Li+ ion and the OH(-) ion can accept three water molecules in most cases. The stabilization energies of hydration for LiOH are calculated to be much larger than those of strong acids such as HCl and H(2)SO(4). The predicted vibrational spectra of each size of clusters indicate an irregular tendency of the stretching frequency of Li-O depending on the number of water molecules.

7

Conformational analysis of 1,2,4,5-tetroxane

Jorge N., Gomez-Vara M., Romero J. R., Castro E. A.

Bulletin of the Polish Academy of Sciences. Chemistry

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2002

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Vol. 50, No. 3

387-395

EN

Different theoretical procedures are applied to make a conformational study of the 1,2,4,5-tetroxane molecule: AMI semi-empirical method, ab initio RHF method at the 3-21+G and 6-311+G(d,p) basis set levels and B3LYP density functional method at the same basis set levels. The molecular stability is analyzed on the basis of different stereo-electronic and symmetry features. There is a general agreement between these methods and all of them predict the chair conformation to be the most stable conformer.

8

Density functional study of hydrogen adsorption on selected transition metals and their alloys

Romanowski S., Pietrzak T., Bartczak W. M.

Bulletin of the Polish Academy of Sciences. Chemistry

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1999

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Vol. 47, No. 2

143-151

EN

The present note shows preliminary results of the non-local density functional calculations of energy of the hydrogen adsorption on the alloys NixCU(1)-x, AgxPd(1)-x, AuxPt(1)-x, where 0 < x < 1. The aim of the calculations was to provide an integrated measure of the catalytic power of a given alloy for the H2 dissociation reaction. It was found that the highest value of the catalytic power is exhibited by Nix CU1-x alloys with x between 0.3 and 0.6 and some AUxPtl-x alloys and the neat metals Ni and Pt.