Basis sets applied to the theoretical study of the vibrational structure of hexaaquaaluminum(III) ion

Gaussian basis sets were developed with the Generator Coordinate Hartree-Fock (GCHF) method for the atoms from H (14s), O (23s16p), and Al (29sl9p) in the ground state. These basis sets were then contracted to 3s (12,1,1), 5s3p (18,2,1,1,1/14,1,1), and 7s5p (20,3,2,1,1,1,1/14,2,1,1,1) for H, O and Al atoms, respectively, by a standard procedure. The quality of contracted basis sets in molecular calculations was evaluated through studies of the total and orbital (epsilon(HOMO) and epsilon(HOMO-1)) energies at the HF level for the hexaaquaaluminum(III) ion, [AI(H(2)O)(6)](3+). For the O atom, the 5s3p was supplemented with d polarization function and it was used in combination with 3s, and 7s5p for H and Al atoms was used to the theoretical interpretation of the Infrared (IR) spectrum of hexaaquaaluminum(III) ion. The calculations of the IR-spectrum were also performed at the HF level and it showed that the basis sets obtained with the aid of GCHF method lead to the selection of useful contracted Gaussian basis sets for the theoretical study of vibrational property of ionic specie of our interest. (C) 2004 Elsevier B.V. All rights reserved.

Experimental and theoretical study of the compound [Pd(dmba)(NCO)(imz)]

The compound [Pd(dmba)(NCO)(imz)] (dmba = N,N-dimethylbenzilamine; NCO = cyanate; imz = imidazole) was studied through experimental and theoretical methods. The complex was synthesized and characterized by IR and NMR spectroscopy. To an appropriate representation of the molecular environment, Gaussian basis sets for the constituent atoms of the compound were built and, after adequate supplementation with polarization and diffuse functions, they were used to study the molecule. Calculations of electronic and vibrational structure of two possible isomers were carried out, showing that the compound, which contains the NCO GROUP trans to the Pd-C bond, is 4.29 kcal/mol more stable than the analogous one, where the imz ligand is trans to the Pd-C bond. The calculated molecular parameters, bond distances, and bond angles showed that the geometry around the metallic center is square-planar with the cyanate being linear. The theoretical infrared spectrum of C(1) symmetry (electronic state (1)A) is in accordance with the experimental one. It also verified the contribution of Pd (4d(xz) + 4d(yz)) and Pd (4d(xy)) in the HOMO and LUMO orbitals, respectively. (c) 2006 Elsevier B.V. All rights reserved.

DFT Study with Inclusion of the Grimme Potential on Anatase TiO2: Structure, Electronic, and Vibrational Analyses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Vibrational-rotational structure of supersingular plus Coulomb potential A/r4 - Z/r*

The vibrational-rotational states of the supersingular plus Coulomb potential A/r4 - Z/r are variationally constructed using a nonorthogonal basis of atomic hydrogenic eigenfunctions modulated by an exponential factor exp(- α/r), ensuring the correct behavior in the vicinity of the supersingularity. The construction is carried out in two successive stages. The first stage is restricted to trial functions without radial nodes, leading to a variational optimization of the parameters of the basis for each value of the angular momentum. The second stage uses the complete basis to construct linear trial functions and to formulate the variational problem in terms of secular equations, yielding the successive vibrational and rotational states. Numerical results for the corresponding energy levels are presented for different combinations of the intensity parameters of the potential. © 2001 Plenum Publishing Corporation.

Structural investigations of tungsten silver phosphate glasses by solid state NMR, vibrational and X-ray absorption near edge spectroscopies

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Molecular structures and vibrational frequencies for [PdX2(tdmPz)] (X = Cl-, SCN-): A DFT study

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Structure Elucidation and Absolute Stereochemistry of Isomeric Monoterpene Chromane Esters

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structural and vibrational analysis of nanocrystalline Ga1-xMnxN films deposited by reactive magnetron sputtering

The structural and vibrational properties of nanocrystalline Ga1-xMnxN films deposited by reactive magnetron sputtering were analyzed in a wide composition range (0 < x < 0.18). The films were structurally characterized using x-ray diffraction with Rietveld refinement. The corresponding vibrational properties were investigated using micro-Raman and Fourier transform infrared spectroscopies. The films present a high crystallized fraction, crystallites having wurtzite structure, and high orientation texture with the c axis oriented perpendicular to the substrate surface. Rietveld analysis indicates that Mn atoms are incorporated substitutionally into Ga positions and show that the ionic character of cation-N bonds along the c axis is favored by the Mn incorporation. No evidence for Mn segregation or Mn rich phases was found in the composition range analyzed. Micro-Raman scattering spectra and infrared absorption experiments showed progressive changes with the increase of x and monotonic shifts of the GaN TO and LO peaks to lower frequencies. The structural and vibrational analyses are compared and the influence of Mn on the static and dynamic properties of the lattice is analyzed. (C) 2007 American Institute of Physics.

Molecular structures and vibrational frequencies for cis-[PdCl2(tmen)] and cis-[Pd(N-3)(2)(tmen)]: A DFT study

Theoretical molecular structures of the complexes cis-[PdCl2(tmen)] and cis-[Pd(N-3)(2)(tmen)] (tmen = N,N,N',N'-tetramethylethylenediamine) were investigated using B3LYP/DFT method. The calculated molecular parameters, bond distances and angles, revealed a square-planar geometry around the metallic center for both compounds with the azide being linear. The theoretical infrared spectra of C, symmetry (electronic state (1)A) of the compounds are in agreement with the experimental data. (C) 2007 Elsevier B.V. All rights reserved.

Vibrational spectroscopy of the seselin crystal

Seselin, C14H12O3, is a coumarin which crystallizes in a monoclinic structure P2(1)/b(C-2h(5)) with four molecules per unit cell. In a Fourier-transform Raman spectroscopic study performed at room temperature, several normal modes were observed. Vibrational wavenumber and wave vector calculations using density functional theory were compared with experiment, which allowed the assignment of a number of normal modes of the crystal. Temperature-dependent Raman spectra were recorded between 10 and 300 K. No anomalies were observed in the phonon spectra, indicating that the monoclinic structure remains stable. Copyright (c) 2007 John Wiley & Sons, Ltd.

Structural and vibrational study of cubic Sb2O3 under high pressure

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Metal carbonyls with zinciron bond: synthesis and vibrational spectra

The compounds of the type LZnFe(CO)4 (L = dien, trien, tn, s-diMeen, Meen) not yet reported and (NH3)3ZnFe(CO)4, already known, were prepared and studied by IR and Raman spectroscopy. The data obtained suggest that LZnFe(CO)4, for L = (NH3)3, dien and trien are monomers with a bipyramidal trigonal configuration around the iron atom, while for L = tn, s-diMeen and Meen the complexes are probably polymers having a center of symmetry with iron atoms octahedrally co-ordinated. © 1979.

Electronic spectra, ESR and crystal structure of tetrahedral halocuprates(II). The existence of cations (2tbpo·H+) with a very short hydrogen bond

Two compounds [2tbpo·H+)2[CuCl4]= (yellow) and (2tbpo·H+)2[CuBr4]= (dark purple) (tbpo = tribenzylphosphine oxide) have been prepared and investigated by means of crystal structure, electronic, vibrational and ESR spectra. The crystal structure of the (2tbpo·H+)2[CuCl4]= complex was determined by three-dimensional X-ray diffraction. The compound crystallizes in the space group P42/n with unit-cell dimensions a = 19.585(2), c = 9.883(1)Å, V = 3790 (1)Å3, Z = 2, Dm = 1.303 (flotation) Dx = 1.302 Mg m-3. The structure was solved by direct methods and refined by blocked full-matrix least-squares to R = 0.053 for 2583 observed reflections. Cu(II) is coordinated to four chlorides in a tetrahedral arrangement. Tribenzylphosphine oxide molecules, related by a centre of inversion, are connected by a short hydrogen bridge. Chemical analysis, electronic and vibrational spectra showed that the bromide compound is similar to the chloride one and can be formulated as (2tbpo·H+)2[CuBr4]=. The position of the dd transition bands, the charge transfer bands, the ESR and the vibrational spectra of both complexes are discussed. The results are compared with analogous complexes cited in the literature. © 1983.