bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonadditive effects in metal clusters and chemisorption. Pseudopotential study of palladium clusters
Authors: García‐Prieto J. , Novaro O. 
Published: December 2004

AbstractThe analysis of nonadditive effects in small palladium clusters via LCAO‐MO‐SCF calculations using the nonempirical pseudopotential model is presented. The results are tentatively correlated with previous studies on various metal clusters (Li, Be, Mg, etc.) for which a good knowledge of multibody terms has provided a valuable guide for understanding the cluster stabilities and their chemisorption capacity.
Uracil and the tautomer 4‐hydroxyuracil: An ab initio study with geometry optimization
Authors: Zielinski Theresa Julia , Shibata Masayuki , Rein Robert 
Published: December 2004

AbstractAb initio STO‐3G geometries and relative energies for uracil (U) and the tautomer 4‐hydroxyuracil (U*) were obtained with the HONDO program utilizing the rapidly convergent method of Murtaugh and Sargent for geometry optimization. ΔE for U⇄U* is 6.61 kcal/mole. The reaction field continuum model for solvent effect indicates a preferential stabilization of U* by 1.0 kcal/mole. The calculated gas phase Kt and solution Kt for U⇄U* are 1.44×10−5 and 1.3×10−4, respectively.
Calculation of isoelectronic energy differences using perturbation theory
Authors: Sontum Stephen F. , Ingraham Lloyd L. , Fink William H. 
Published: December 2004

AbstractEnergy difference formulas for isoelectronic processes are derived using a perturbation series. The perturbed Hamiltonian is written as a function of a perturbation parameter that changes linearly from zero to one between the limits of the isoelectronic process. The perturbation series is based on a zero order wave function obtained when the perturbation parameter has a value of ½. For the description of changes of electronic energy with internuclear geometry, this zero order wave function will correspond to the solution of a Hamiltonian which contains atoms from both internuclear geometries, but with half their normal nuclear charge. Energy differences calculated with this formalism for the stretching of simple diatomic molecules hydrogen fluoride, fluorine, and carbon monoxide and the rotational barrier in ethane are compared with results from restricted Hartree–Fock and integral‐Hellmann–Feynman theorem energies.
Nodeless wave functions and spiky potentials
Authors: Hunter Geoffrey 
Published: December 2004

AbstractThe exact (nonadiabatic) nuclear and electronic factors of a molecular wave function are expanded in the basis of eigenfunctions of the electronic Hamiltonian according to the Rayleigh–Schrödinger perturbation theory of Born and Huang. Thus it is shown that, with rare exceptions, the exact nuclear factor (a marginal amplitude) is a nodeless function. The nodes in vibrationally excited nuclear wave functions within the Born–Oppenheimer approximation become node‐avoiding minima in the exact nuclear wave function. Corresponding to each node‐avoiding minimum in the nuclear wave function the exact (nonadiabatic) effective potential for the nuclear motion has a spiky barrier superimposed upon the Born–Oppenheimer (adiabatic) eigenenergy of the electronic Hamiltonian. These barriers are the result of nonadiabatic coupling between electronic states, which is strongest in the vicinity of the nodes in the Born–Oppenheimer‐approximation nuclear (vibrational) wave function.
Bond–antibond analysis of internal rotation barriers in glyoxal and related molecules: Where INDO fails
Authors: Tyrrell J. , Weinstock R. B. , Weinhold F. 
Published: December 2004

AbstractAb initio and INDO LCBO–MO calculations are carried out on glyoxal, 1,3‐butadiene, and acrolein in order to analyze the qualitative failure of INDO‐like methods to describe conformation energies in these molecules. Following the method of Brunck and Weinhold for ethanelike systems we identify the principal bond–antibond interactions contributing to the glyoxal barrier, their dependence on dihedral angle and substituent, and their relative magnitudes as calculated by ab initio and INDO SCF–MO theory. We find a gross disparity in the INDO representation of π* interactions which leads to a grossly exaggerated estimate of the stability of gauche conformers in these molecules. These findings appear to have serious implications for the applicability of INDO‐like theories to conformational problems in π‐bonded molecules, including those of biological interest.
An einstein relativistic atomic and molecular model based on the Horwitz–Piron–Reuse theory
Authors: Grelland Hans H. 
Published: December 2004

AbstractThe Einsteinian quantum mechanics proposed by Horwitz, Piron, and Reuse is formulated in a way appropriate for atomic and molecular calculations. In this theory each particle is described by a four‐coordinate xμ = (ct, x), and the existence of a common Lorenz invariant time ordering parameter τ is postulated. For spin‐½ particles there exists in addition a superselection rule n defined by the Stern–Gerlach experiment. The description of an atom/molecule in the external approximation is given. We then formulate a method (the self‐consistent energy method) by which conventional calculation procedures can be applied within the theory. The calculation of the expectation value of a singular term which is the analog of the conventional Darwin term, is demonstrated by calculating the energy of an electron in a Coulomb field to the order α4. This calculation also demonstrates the validity of the Pauli approximation within the theory.
Use of iterative natural orbital method for calculating energy barrier to predissociation of the first excited states of NH3 (3s1,3A″2)
Authors: Müller Jiri 
Published: December 2004

AbstractThe barrier to predissociation of the first excited states of NH3 (3s1,3 A) is computed from a truncated first‐order wave function using the iterative natural orbital method. The results show that the barrier is lower than when calculated with RHF and the CI wave functions, where single and double replacements to a truncated virtual space are carried out. These findings are used to interpret experimental data.
Mode of action and quantitative structure–activity relationship of sulfonamides in biological systems of different complexity (enzymes, bacteria, rat, and human)
Authors: Seydel J. K. 
Published: December 2004

AbstractThe mode of action of sulfonamides is evaluated and described and the structural dependency of the inhibitory effect of sulfonamides against isolated enzymes as well as against whole cell bacteria is quantitatively described as a function of the variation of electronic and steric influences of the various substituents. In addition the structural dependence of various pharmacokinetic properties as rate of absorption, distribution, metabolism, and excretion on structural changes in the sulfonamide molecules is quantitatively derived. In contrast to the preconditions for inhibitory activity, changes in lipophilicity play the dominant role in pharmacokinetics of sulfonamides.
Explicit expression of the franck–condon factors in terms of the potentials of the two states
Authors: Kobeissi Hafez , Dagher Mounzer , Alameddine Mohamad Adel 
Published: December 2004

AbstractThe calculus of the overlap integral for two states represented by the vibrational wave functions ψ and ψ is reduced to that of the Franck–Condon integral ℒ(0, x) = ∫ ψψ (t) dt. It is proved that for “numerical potentials” (as well as for a Dunham potential), this integral is given on each interval by a simple analytic expression in terms of the two potentials. The Franck–Condon factors are well determined by “coupling constants” related uniquely to the coordinates of the turning points of the potentials. An application to the band system BIIXΣ of Nα2 is compared with the usual numerical methods.
Treatment of excited states in the CASSCF method: Application to BO
Authors: Almlöf J. , Nemukhin A. V. , Heiberg A. 
Published: December 2004

AbstractThe CASSCF method has been applied to some excited states of the BO molecule. Only portions of the full potential curves could be obtained with the help of the usual two‐step procedure. It was possible to complete the curves and to consider other excited states by using an averaged field technique. In this approach the energies were computed with orbitals that were self‐consistently determined with first‐ and second‐order density matrices averaged over several states.
Complex coordinate rotation calculation of branching ratios
Authors: Bačić Zlatko , Simons Jack 
Published: December 2004

AbstractIt is shown how branching ratios can be obtained from complex coordinate rotation calculations. The procedure is applied to a rotational Feshbach resonance in a model atom‐diatom van der Waals complex which has two open channels present, and to a simple two‐channel model potential problem which has been treated by other workers.
Calculation in K space of integrals arising in the theory of Van Der Waals forces
Authors: Malinowski P. , Tanner A. C. , Lee K. F. , Linder B. 
Published: December 2004

AbstractWe derive basic integrals needed for calculation of matrix elements of the Fourier transformed Coulomb operator and the Fourier transformed square of the Coulomb operator between 1s Slater functions. These integrals arise, for example, in the momentum space (k space) susceptibility formulation of van der Waals forces. The advantages of integration in k space (rather than r space) are that in k space there is a drastic reduction in the number of integration variables, and contour integration can be used. The derivation is completely analytic and the auxiliary integrals are all obtained in closed form.
Intermolecular and intramolecular interactions calculated with ab initio perturbative configuration interaction method using strongly localized orbitals
Authors: Otto P. , Ladik J. 
Published: December 2004

AbstractWe have applied the ab initio formulation of the perturbative configuration interaction using localized orbitals (PCILO) method up to third order to calculate intermolecular and intramolecular interaction energies going beyond the ab initio Hartree–Fock calculation. For the rotational barrier in ethane our results agree well with the experimental value and the cis‐ and even the trans‐barriers in HOOH are at least qualitatively reproduced with the aid of the STO‐3G basis set. In the case of the water dimer we obtain an equilibrium intermolecular distance and interaction energy which are confirmed by other calculations. We can further conclude from our studies that one has to include higher orders in the perturbation expansion as the system becomes more complicated. It is especially the last aspect which hinders the application of the ab initio PCILO to estimate the major part of the electron correlation energy for large molecules.
CrCr Multiple bonding in binuclear complexes
Authors: De Mello Paulo Corrêa , Edwards W. Daniel , Zerner Michael C. 
Published: December 2004

AbstractA simple analysis of the bonding between the d orbitals in binuclear complexes of chromium indicate that the usual multiple bond picture used to describe these systems is incomplete. This analysis is fairly general and depends only on the symmetry of these complexes and the rather weak coupling between the 3d orbitals on the two metal centers. A series of INDO calculations on Cr2Cl8−4 and Cr2(CH3)8−4 are reported, and suggest that the dominant description of the bonding is one of two Cr atoms antiferromagnetically coupled. Although this description properly accounts for the eclipsed versus staggered conformations found for these systems, the calculated bond length is too long. An analysis of the components of the wave function suggests that the role of multiple bonded structures (configurations) may be small but is important in its influence in shifting the very flat potential energy surfaces to shorter CrCr distances.
Electronic structure and vertical excitation spectrum of methylene amidogen CH2N
Authors: Adams George F. , Yarkony David R. , Bartlett Rodney J. , Purvis George D. 
Published: December 2004

AbstractAb initio electronic structure calculations are reported for five electronic states of the methylene amidogen radical. Structure parameters for the ground electronic state are predicted by RHF and D‐MBPT (4) calculations. Vertical excitation energies were determined using four different theoretical chemical models: complete active space (CAS) MCSCF, CAS/MCSCF plus singles and doubles Cl, fourth‐order many‐body perturbation theory SDQ‐MBPT(4), and coupled‐cluster theory.
Semiclassical time‐correlation function approach to collisional energy transfer into many‐atom systems
Authors: Micha David A. 
Published: December 2004

AbstractCross sections for energy transfer into many‐body systems can be expressed in terms of time‐correlation functions (TCFS) of transition operators. A semiclassical version is presented by treating internal motions as quantized and relative motions as classical. The time evolution of internal motions can be calculated in the Heisenberg picture and avoids expansions in target states. The decoupling of fast and slow internal motions is treated and applied to vibrational–rotational decoupling in polyatomic molecules. Results are presented for Li+‐CO2 collisions.
Core hole induced charge‐transfer reactions in disubstituted benzenes
Authors: Ågren Hans 
Published: December 2004

AbstractThe application of the charge‐transfer concept on core electron ionization in donor–acceptor molecules is analyzed. A single excitation picture, involving the highest occupied and lowest unoccupied molecular orbitals is compared with a full π‐valence orbital active space model. The connections between the notion of charge transfer in donor–acceptor species with the shake‐up picture used for core photoelectron spectra of small molecules and with the dynamical screening concept applied on surface–adsorbate spectra are discussed.
Interacting stereo‐irregular chains: A model for conducting polymers
Authors: Stafström S. , Riklund R. , Chao K. A. 
Published: December 2004

AbstractInteracting stereo‐irregular chains of hydrogen atoms, which simulate the topological structure of many conducting polymers, are generated by a computer and solved numerically with the unrestricted Hartree–Fock method with a modified spin polarized potential. The electron localization is investigated, and a mechanism for the interchain tunneling is discovered. Local antiferromagnetic ordering is derived which may explain the AF behavior observed in some conducting polymers.
Random‐walk theory for localization
Authors: Chaturvedi Meena , Srivastava Vipin 
Published: December 2004

AbstractA continuous‐time random‐walk theory has been developed for Anderson localization. On a continuous time scale random walks are performed along extended (i.e., propagating) and localized (i.e., trap) states. Complete information of disorder is contained in a distribution function called “hopping time distribution function” ψnm(t), which gives the probability per unit time for transition from state m to state n in time t. The “stay‐put” probability 𝒫(t = ∞), which is the probability to rediscover an excitation at a site “0” at time t = ∞ if it was there at t = 0, is obtained in terms of ψnm(t). Appropriate forms for ψnm(t) are constructed which are in conformity with the photoconductivity experiments on dispersive transport, and 𝒫(∞) are calculated. The results indicate that the entire spectrum consists of three regimes, namely, those of (i) “diffusion,” (ii) “weak diffusion,” and (iii) “no diffusion,” which, respectively, designate the extension, the power‐law localization, and the exponential localization of states. The results also shed light on the question of “continuous or discontinuous (?)” transition across the mobility edge.
Application of photoelectron spectroscopy to biologically active molecules and their constituent parts. IX. 1,4‐Benzodiazepin‐2‐ones
Authors: Klasinc L. , Ruščić B. , Sabljić A. , Trinajstić N. 
Published: December 2004

AbstractThe Hel photoelectron (PE) spectra of desmethyldiazepam, diazepam, oxazepam, temazepam, 3‐(S)‐methyldesmethyldiazepam, 3‐(S)‐methyldiazepam, 5‐methyl‐2H‐1,4‐benzodiazepin‐2‐one, and benzophenonmethylimine have been measured and analyzed. Their low‐energy regions (up to 12.0 eV) have been completely assigned by the composite molecule method using the PE spectra of diphenylmethane, benzophenonmethylimine, acetamide, chlorobenzene, and acetophenonmethylimine to compare the electronic structure of equivalent parts.
Managing build‐to‐order short life‐cycle products: benefits of pre‐season price incentives with standardization
Authors: Weng Z.Kevin , Parlar Mahmut 
Published: December 2004

AbstractIn this paper we consider a firm that can produce standardized products (SP) or customized build‐to‐order products (BOP) with short life‐cycles. We develop a stochastic dynamic programming model to study the effect of offering price incentives to those customers who are willing to commit themselves to purchasing the cheaper‐to‐produce standardized product. The market’s reaction to price incentives is captured by modeling the probabilistic behavior of two exclusive groups of customers who may be “price‐sensitive” or “price‐insensitive” and who are willing to commit themselves. We develop an analytic expression for the distribution of the demand for the BOP conditional on the actual number of committed demands for SP following the price‐incentive announcement. We show that price incentives expand the total expected demand while reducing demand uncertainty and we present conditions under which it is optimal to offer a price incentive. Sequentially made price incentive and capacity decisions for the BOP that maximize expected profit are obtained by solving the dynamic programming problem. We provide a comparative statics analysis and examine the effect of varying parameter values on the optimal price‐incentive discount rate. We also describe a numerical study and present a sensitivity analysis of the profit improvement obtained after offering price incentives. We show that for low purchase probability, large number of customers in the price‐sensitive group and high profit margin price incentives can substantially improve the expected profit.
Money and macroeconomic performance: revisiting divisia money
Authors: Darrat Ali F. , Chopin Marc C. , Lobo Bento J. 
Published: December 2004

AbstractRecent research suggests that the relation between money and the macroeconomy has sharply weakened in the U.S. after 1980. We reexamine this alleged breakdown by testing for cointegration between the macroeconomy and simple‐sum and Divisia monetary aggregates. We check the robustness of our results by modeling multiple key breakpoints around the early 1980s. Unlike the case of simple‐sum monetary aggregates, the evidence is overwhelming in its support for cointegration between Divisia money and macroeconomic variables, which persists despite several policy shifts and dramatic financial innovations in the post‐1980 period. These results support Divisia money over simple‐sum monetary aggregates as a guide in the implementation of monetary policy.
Some cytokine profiles of  T‐helper cells in lesions of advanced periodontitis
Authors: Berglundh Tord , Liljenberg Birgitta , Lindhe Jan 
Published: December 2004

AbstractObjective: The aim of the present study was to analyze some cytokine profiles of T‐helper cells in periodontitis lesions.Material and methods: 22 adult patients (7 females and 15 males, aged 24–66 years) with advanced and generalized chronic periodontitis were recruited. Clinical and radiographical characteristics of periodontal disease was assessed. From each patient a gingival biopsy was obtained from one randomly selected diseased interproximal site. The soft tissue sample was prepared for immunohistochemical analysis. Double staining was performed to detect cells positive for both the CD4 marker and different cytokines, i.e. interleukin (IL)‐2, IL‐4, IL‐6 and interferon‐gamma (IFN‐γ).Results:  The lesions in advanced periodontitis contained similar proportions of cells positive for the different cytokine markers examined. In addition, the number of cells expressing cytokine profiles for either T helper‐1 (IFN‐γ + IL‐2) or T helper‐2 (IL‐4 + IL‐6) was similar.Conclusion:  It is suggested that the lesions of periodontitis are regulated by a combined Th‐1 and Th‐2 function.
Effect of treatment of chronic periodontitis on levels of serum markers of acute‐phase inflammatory and vascular responses
Authors: Ide M. , McPartlin D. , Coward P.Y. , Crook M. , Lumb P. , Wilson R.F. 
Published: December 2004

AbstractAims:  Recent epidemiological work suggests an association between periodontal disease severity and cardiovascular disease risk. This study aimed to ascertain if circulating levels of cardiovascular and systemic inflammatory markers could be modified following treatment of periodontal disease.Method:  Adult subjects were recruited from those awaiting periodontal treatment and randomised to either immediate (test, n=24) or delayed treatment (control, n=15). Demographic and clinical data were collected and venous blood was taken before and either 6 weeks after completion of treatment or after an equivalent 3‐month control period. Periodontal examination included probing depth, loss of attachment, plaque scores and bleeding scores. Blood was analysed to determine serum and plasma fibrinogen, C‐reactive protein, sialic acid, tumour necrosis factor‐α and interleukin ‐6 and ‐1β. Effects of treatment were assessed by paired tests and analysis of variance by treatment group with baseline covariates.Results:  Treatment improved plaque and bleeding scores and reduced probing depths (p<0.002). However, there were no statistically significant changes in levels of any of the systemic markers.Conclusion:  Improvement in periodontal health did not influence the levels of vascular markers.