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I review two new ideas for coping with the size of large product basis sets and large product grids when one computes vibrational energy levels. The first is based on a tensor reduction scheme. It exploits advantages of a sum-of-products potential. The key idea is to use a basis each of whose function is a sum of optimized products and to compress the number of terms in each basis function. When the potential does not have the sum-of-products form, it is usually necessary to use quadrature. The second idea uses a nondirect product grid that has structure and is therefore compatible with efficient matrix-vector products. Key words: theory, rovibrational spectroscopy, iterative methods, Lanczos algorithm. Cet article decrit deux nouvelles approches permettant l'utilisation d'une grande base de produits afin de calculer des niveaux vibrationnels. La premiere est fondee sur la reduction des tenseurs. Elle exploite les avantages d'un potentiel ayant la forme d'une somme de produits. L'idee clef est d'utiliser une base dont chacune des fonctions est une somme de produits optimises et de comprimer le nombre de termes dans chaque fonction de la base. Si le potentiel n'est pas une somme de produits, il faut utiliser une quadrature. La seconde approche consiste a utiliser une grille qui n'est pas un produit direct mais qui a assez de structure pour faciliter le calcul de produits matrice-vecteur. Mots-cles: theorie, spectroscopie rotationnelle-vibrationnelle, methodes iteratives, algorithme de Lanczos., Introduction Most methods for solving the vibrational Schroedinger equation obtain energy levels by representing wave functions as linear combinations of basis functions, and making and solving a matrix eigenvalue problem. [...]

The unsaturated D3C compounds were investigated at the molecular level using accurate quantum mechanical methods. The results indicated that the C=C double bond location imposes significant effects on the ionization potentials of D3C compounds and the inner shell binding energy spectral variations with respect to the C=C bond exhibit more site dependence.

Ab initio molecular electronic structure theory is used to calculate the [sigma]- and [pi]-bond strengths for the molecules B[H.sub.2]N[H.sub.2], B[H.sub.2]P[H.sub.2], Al[H.sub.2]N[H.sub.2] and Al[H.sub.2]P[H.sub.2]. The adiabatic [sigma]-bond energy is described as the dissociation energy of A[H.sub.2]X[H.sub.2] to A[H.sub.2] X[H.sub.2] in their ground states minus the adiabatic [pi]-bond energy.

The straightforward application of the interacting quantum atoms (IQA)/quantum theory of atoms in molecules (QTAM) approach to the decomposition of the binding energy of first row diatomics into self-and interaction components has provided a complementary new way to rationalize the experimental facts. The ability of the IQA approach to generate sensible atomic self-energies that hide all the important cancellations of the usual energetic terms of quantum chemistry might be used to introduce new complementary ways of understanding the chemical phenomena.

The electronic properties of delta-doped In0.22Ga0.78As/GaAs quantum wells (QWs) are studied by van der Pauw Hall measurements and Shubnikov-de Haas measurements. From the temperature-dependent van der Pauw Hall measurements, two kinds of donors are observed, which have binding energies of 104 (plusmn) 7 and 9.6 (plusmn) 0.1 MeV.

The stability of the Pt-3d-Pt(111) (3d = Ti, V, Cr, Mn, Fe, Co, or Ni) bimetallic surface structures in the presence of adsorbed oxygen is investigated by means of density functional theory, and the binding energies of oxygen on Pt-3d-Pt(111) and 3d-Pt-Pt(111) are calculated. All the Pt-3d-Pt(111) surfaces are found to have weaker oxygen binding energies than pure Pt(111) whereas all of the 3d-Pt-Pt(111) surfaces are found to have stronger oxygen binding energies than pure Pt(111).

The binding energies and the corresponding structures of a methane molecule on the silanol covered 010 surface of silicate-I was investigated using ab inito methods. The results showed that the methane molecule will relatively seldom be absorbed on the silanol covered 010 surface of silicate-1, instead the adsorption process will take place directly at the center of the straight channel.

Atomistic semiempirical quantum mechanical calculations were performed on the interaction between CdSe and CdSe/CdS core/shell nanocrystals and MPOH. Results suggest that the experimentally observed changes in binding energy are due to the distribution of surface facets on the nanocrystals and not related to band gap.

A tight-binding parameter extraction scheme that is suitable for the modeling of intermetallic alloy systems is implemented. Augmented by a fitted repulsive energy contribution that takes the form of embedded atom potential, the tight-binding total energy method is applied in Monte Carlo simulations to compute the coefficients of thermal expansion for Mo3Si.

The low energy isomers of p-carboxyl styrene dimer structures and their relative and binding energies are determined using both Moller-Plesset second-order perbutation theory (MP2) and the general effective fragment potential (EFP2) method. The EFP2 and MP2 methods agree with regard to the relative energies of most isomers, with the exception of isomer 6, for which these two methods predict binding energies that differ by approximately 6 kcal/mol.

Ab initio calculations and the density of states (DOS) of V2AlC study the structure of V2AlC for antiferromagnetic, ferromagnetic and paramagnetic configurations are discussed. The analysis of DOS and cohesive energy indicates that no significant stability differences between spin-polarized and non-spin-polarized configurations.

The photolysis and rebinding kinetics of carboxy-myoglobin (MbCO) embedded in a trehalose glass at room temperature using transient absorption and diffractive optics-based phase grating spectroscopy on nanosecond to microsecond time scale was investigated. The result suggests that protein structure plays a significant role in the bond energies at active sites which in turn provides a tuning element of the effective barrier heights independent to the transition state region.

Ab initio multireference single- and double-excitation configuration interaction calculations are carried out to study the interactions of positrons with the members of the alkali hydride class of molecules. A new computer program is constructed for this purpose that makes use of the able-Direct-CI method for construction of the required Hamiltonian matrixes and electronic/positronic wave functions.

A series of density functional calculations were performed on several substituted fullerenes to determine the relationship among curvature, patch type, and reactivity of the C-C site. It was found that the binding energy between the Pt(PH3)2 unit and fullerene is almost independent of the size of the cage and of the number of metals coordinated on the fulerene surface.

Infrared photodissociation spectra of (benzene-water-Ar)(super +) in the 3 micrometer region are observed by monitoring benzene(super +) and (benzene-water)(super +) fragments. The appearance energies of the predissociation channels observed in the IRPD spectra of the (benzene-water-AR)(super +) cluster cation with some postulates are investigated.

A demonstration on the operation of an abstraction channel in the chemisorptions of O2 on Al(111) is presented. The study concluded that in the O2/Al(111) interaction ordinary chemisorptions is hampered because of the slow spin transition whereas the abstraction channel is open due to the large oxygen atom binding energy to Al(111), in contract to transition-metal surfaces.

Periodic, density functional theory (DFT-GGA) calculations, using PW91 (self-consistently) and RPBE functionals, are employed to determine preferred binding sites, adsorbate structures, and binding energies for the adsorption of atomic (H, N, O, S, and C), molecular (NO and CO), and radical (OH) species on Cu(111) and CuSn(0001) alloy surfaces. The results indicated the following order in the binding energies from the least to the most strongly bound: NO < CO < H < OH < N < O < S < C for Cu-terminated CuSn(0001).

Byline: Francisco M. Fernandez (1), Eduardo A. Castro (1) Keywords: bond stretching; bond bending; molecular interactions; potential-energy functions; molecular mechanics; mathematical relationships Abstract: We analyse recently proposed connection formulas between potential-energy functions for bond stretching, bond bending and molecular interactions, and propose more convenient and practical expressions. For example, our mathematical relationships between Morse and Murrel--Mottram potential parameters yield much closer agreement between such potential-energy functions. Author Affiliation: (1) INIFTA (Conicet, UNL P), Diag. 113 y 64 (S/N), Sucursal 4, Casilla de Correo 16, 1900, La Plata, Argentina Article History: Registration Date: 07/10/2004

Direct wafer bonding of silicon wafers is a promising technology for manufacturing three-dimensional complex microelectromechanical systems as well as silicon-on-insulator substrates. A bearing depth of ~1.4 nm was found to be appropriate for the characterization of direct-bonded silicon at room temperature, which is consistent with thickness of the water layer at the interface responsible for hydrogen bonds that link the mating wafers.

N-H bond dissociation energies (BDEs) and radical stabilization energies (RSEs) associated with the .NHCF3, .NHCHO, .NHCOCH3 and .NHCONH2 radicals are calculated at a number of theoretical levels. The performance of the various levels of theory in calculating the BDEs and RSEs of the NHX radicals are assessed.

A relationship is developed to reliably predict known BDE[LnO], BDE[LnO(super +)], BDE[AnO], BDE[AnO(super +)] energies from spectroscopically determined electronic properties. This relationship is employed to estimate unknown bond energies.

The computation of absolute binding affinities by molecular dynamics (MD) based free energy simulations is analyzed, and an exact method to carry out such a computation is presented. Although the techniques were originally developed for the gas phase, the resulting expression is exact, since all contributions from solute-solvent interactions cancel from the final result.

The general applicability of bond-order and bonding-energy methods are explored by investigating how basis-set and functional dependence, and the choice of fragments affect the correlations and complementary nature of these analytical techniques. The results obtained from population analysis are found to be qualitatively consistent with those provided by bonding-energy approaches for basis sets of triple-Xi quality and all functional tested.

The reaction of the phthalmide N-Oxyl (PINO) radical with several hydrocarbons having different C-H bond dissociation energies (BDEs) was investigated in HOAc at 25 degree Celsius. The comparison of the PINO radical reactions with analogous hydrogen atom abstraction reactions of the dibromide radical implies that HBr2 reactions are more exothermic than the PINO radical reactions.

A method for constructing Marks' decahedral lattice for the studies of Lennard-Jones cluster structures is proposed. By comparing the energies of these Marks' decahedral structures, the growth sequences with different structural characteristics, denoted by term 'family', are investigated. It is found that the structures with lowest energies are not always attributed to the even families.

Thermally grown SiO2 layers on Si (100) substrate are subjected to different external voltage bias during XPS analysis to induce changes in the measured binding energy difference Si(super 4+) and Si(super 0) in Si2p and Si(sub KLL) regions. The application of negative d.c. bias increases the binding energy difference, whereas positive bias decreases it.

The crystal structure of the Michaelis complex between the Fab fragment of ferrochelatase antibody 7G12 and its substrate mesoporphyrin has been solved to 2.6-[Angstrom] resolution. The antibody-bound mesoporphyrin clearly adopts a nonplanar conformation and reveals that the antibody catalyzes the porphyrin metallation reaction by straining/distorting the bound substrate toward the transition-state configuration. The crystal structures of the Fab fragment of the germ-line precursor antibody to 7G12 and its complex with the hapten N-methylmesoporphyrin have also been solved. A comparison of these structures with the corresponding structures of the affinity-matured antibody 7G12 reveals the molecular mechanism by which the immune system evolves binding energy to catalyze this reaction.

Research describes the reactivity of Os(H)(sub)3CIL(sub)2 toward vinyl fluorides. The reaction produces OsHFCl(identical CCH(sub)3)L(sub)2 and hydrogen, the latter converting vinyl fluoride to ethylene and hydrogen fluoride.

Results point out that the tight-binding and adjacent matrix method enables to determine the relative energetics or stabilities of the positional isomers of a heteronuclear cluster. Data indicate that the method is simple and efficient in predicting the relative stabilities of positional isomers of heteronuclear clusters.

Analysis of the mutants of adenosine 3',5'-cyclic monophosphate receptor protein from Escherichia coli is discussed with respect to thermodynamic linkage in cyclic AMP binding processes. Results demonstrate that the perturbation of site-site communication in the binding process and the mutations do not perturb signaling pathways, suggesting that the enzyme exists as an ensemble of subunits whose distribution is altered by the mutations.

Results demonstrate that the locked nucleic acid (LNA) bases are strong and selective telomerase inhibitors both in vitro and in vivo. Data indicate that the inhibition is due to the high-affinity hybridization by the LNAs and LNA-DNA chimera.

The theoretical calculation of gas-phase sodium binding energies of common matrix-assisted laser desorption /ionization (MALDI) matrices is presented. It is compared with the experimental results obtained by the ligand-exchange equilibrium method and is found to be in good agreement with the results.

Results indicate that the cationic headgroups and aliphatic tails of lipids are evenly distributed and laid down on DNA surface without forming micelles. The binding is weaker at high salt and temperature conditions with trimethylalkylammonium ligands binding is weaker than alkylamonium ligands.

Research demonstrates the impact of aminoglycoside structural alterations on the thermodynamics of binding to an A-site of 16S rRNA oligonucleotide. Results reveal that aminoglycoside binding enhances the thermal stability of the RNA duplex A-site and the binding is accompanied by proton uptake.

Research elucidates the conformational behavior of S-adenosylmethionine and the sulfonium ions, S-methylmethionine and dimethylsulfonioproprionic by nuclear magnetic resonance spectroscopy and computational anylysis. Data indicate that the sulfonium sulfur is in van der Waals contact with a protein heteroatom in protein complexes.

A study of the high-level ab initio calculations, using the Cpd-G2thaw and CP-G2 composite computational procedures for the bonding between metal monocations NA(sup +), Mg(sup +), Al(sup +), K(sup +) and Ca(sup +) and the radicals H, CH(sub 3), C(sub 2)H(sub 2), C(sub 2)H(sub 3) and C(sub 2)H (sub 5) is presented. The results suggests that radicals such as H and CH(sub 3) encountered in the environment such as jovian planetary atmospheres, outflowing circumstellar envelopes, and interstellar clouds, would display a high selectivity in their propensity to react with ambient metal ions.

The gating and conductance of Escherichia coli polyhydroxybutyrate/polyphosphate and its synthetic version channels, in planar lipid bilayers, behave differently at elevated temperatures. Results reveal that between 25 C and approximately 40 C, both channels show increased conductance and above 40 C only the natural channel conductance show increases with the synthetic channel conductance leveling off.

Results point out the 9R-methylbiotins, analogue of biotin, binds to streptavidin/avidin more tightly than biotin due to the relative solvation free energies of the analogue as shown by binding free energy and solvation free energy calculations and X-ray analysis of the binding modes.

Results indicate that the hydrophobic effect does not contribute much to the energetics of sequence-specific association of the DNA-binding domain of the murine PU.1 transcription factor to the gamma B site of the murine immunoglobulingamma 2-4 enhancer.