摘要:

The effect of polarization of a macroion dielectric by other charged particles in a solution on the pair correlation function of macroions is considered. The effect is shown to be significant in modifying the macroion-macroion interaction in a mixture of weakly charged and strongly charged macroions, and is incorporated in the expression of the potential energy of the Coulomb interaction through a modified screening constant. Its expression for a pair of interacting macroions with spherically symmetric surface charge distribution and the corresponding expression for the interaction of an ion with a polarizable macroion with a non-centrosymmetric surface charge distribution are derived. The expression of shielded Coulomb potential in the former case is derived and is used in numerical calculations of the pair correlation function of a mixture of weakly charged and strongly charged macroions using Allnatt's hypernetted chain equation. The principal qualitative result is enhanced particle clustering. The system parameters that enhance this effect are highlighted. Recent experiments and theories on particle clustering and phase separation in mixtures of macroparticles are discussed.

ISSN:0026-8976    

DOI:10.1080/00268979600100371

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Earlier work has used the concepts of density functional theory to achieve useful estimates of both atomic and diatomic molecular correlation energies. In the present work, some of these ideas are combined with more conventional chemical ideas relating to bond order to evaluate correlation energies in some thirty polyatomic molecules. There are a number of empirical parameters in the present modelling process, but once these are fixed on some 16 molecules the correlation energies in the remaining molecules follow quantitatively, without any adjustments.

ISSN:0026-8976    

DOI:10.1080/00268979600100381

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The interaction energies between two He atoms, two Ne atoms and two Ar atoms were calculated first at the HF-SCF level by a new decomposition scheme using separated molecular orbitals (SMOs). Special attention was paid to the effect of the counterpoise (CP) method. The results show that the CP procedure is an acceptable device for estimating some basis set deficiencies in the systems studied. When using the SMO-LMBPT scheme, on the other hand, the CP calculations become unnecessary. The correlation energy in some Henand Nen(n= 2, 3, 4) clusters have been studied using the SMO-LMBPT formalism at the second, third and fourth levels of MBPT. The effect of the CP method on the intracorrelated parts was studied and the conclusions are similar to those obtained at the HF-SCF level. Both the intra- and intercorrelated parts, as expected, show transferability properties in the systems studied.

ISSN:0026-8976    

DOI:10.1080/00268979600100391

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The vibration-rotation spectrum of vinyl fluoride has been investigated in thev4band region around 1656 cm-1at a resolution of about 0·003 cm-1using a Fourier transform infrared spectrometer. This fundamental of symmetry species A′ is mainly affected by first-orderb-Coriolis resonance with the close-lyingv8+v12and 2v9+v12levels. The rovibrational analysis led to the identification of about 2000 lines withJˇ- 58 andKaˇ- 16 of the predominanta-type component. Using Watson's A-reduction Hamiltonian in theIrrepresentation, a set of effective constants for thev4band was obtained employing transitions free of major resonance contribution. Even though no direct transitions to the perturbing levels have been observed, the determination of a few constants for the perturberv8+v12has been achieved.

ISSN:0026-8976    

DOI:10.1080/00268979600100401

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A mathematical discussion is provided on the relationship between Baxter's adhesive hard sphere fluid and the hard sphere Yukawa fluid with sufficiently strong and short range attractive Yukawa tails. It is proved that the Percus-Yevick approximate solution of the Ornstein-Zernike equation for the former fluid can be included mathematically in the generalized mean-spherical approximation solution with the Yukawa closure, and the equivalence conditions of both solutions are presented.

ISSN:0026-8976    

DOI:10.1080/00268979600100411

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The influence of a static homogeneous applied electric fieldEon the vapour-liquid phase equilibrium of Stockmayer fluids is investigated by two methods. The first is an extension of Gubbins-Pople-Stell perturbation theory (PT) of polar liquids in the presence of an applied electric field. This paper proposes a new simulation technique, theNpTEplus test particle method, developed to determine the vapour-liquid equilibrium of polar fluids in the presence of an applied field. It is based on the three-dimensional Taylor series expansion of the thermodynamic function ỹ (this is the Legendre transformation of the chemical potentialgwith respect to the polarizationm: ỹ = β[gtilde] = β(g-mE) as a function of the intensive parameters β,pandEup to third order around a suitably selected raw point (β0,p0,E0). The zero order term comes from the test particle method; the first- and higher-order coefficients of the series can be derived from running averages and fluctuation formulas, respectively, by performing Monte Carlo simulations for a gas and a liquid phase raw point. The condition of the equilibrium is the equality of the functions ỹ in the two phases.

ISSN:0026-8976    

DOI:10.1080/00268979600100421

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A symmetrical formulation of Poisson-Boltzmann and modified Poisson-Boltzmann theories is used to study aqueous solutions of polyelectrolyte-simple electrolyte mixtures or solutions of macroions, counterions and neutral particles. The solutions are modelled by a three-species primitive model electrolyte in which the particles are asymmetrical in charge and size. The predicted correlation functions are found to be in reasonable agreement with those from hypernetted chain calculations. An interesting feature of the structure observed in the theoretical calculations is that, due to collective effects between the species under certain physical conditions, an attractive force can exist between two polyions. Donnan pressures and potentials are calculated for the polyelectrolyte-electrolyte solution.

ISSN:0026-8976    

DOI:10.1080/00268979600100431

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The pump-probe stimulated emission signals from the electron transfer system in a condensed phase are studied theoretically. To show how the system dynamics affect the stimulated emission signal, both weak and strong electronic coupling cases are investigated. The effects of temperature on the dynamics of the system are reported.

ISSN:0026-8976    

DOI:10.1080/00268979600100441

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

An automatic quantum-based method to find and extract the relevant localizations of a dynamical system is presented and applied to three-dimensional H+3vibrational calculations. The method exploits the relationship between expressions in the time domain and the energy domain, extracting from groups of eigenstates the localization information related to short term structures in the dynamics. Several localizations are found and extracted. Special emphasis is placed on bending and dissociating motions.

ISSN:0026-8976    

DOI:10.1080/00268979600100451

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The shapes of spinning sidebands for13C magic-angle spinning spectra of solids affected by residual dipolar splittings to14N are found to be spinning-speed dependent. Simple theory for the case of co-axial tensors indicates that centreband splittings at low spinning speeds yield values ofxD(xandDare quadrupolar and dipolar coupling constants respectively) directly. The case of the cyanide carbon resonances for the coordination polymer [ᵵ(CH3)3Pb∼4Ru(CN)6]∞is considered in detail. Computer simulations of the sideband bandshapes fit the experimental results well. The quadrupole coupling constants for the three cyanide nitrogen sites lie in the range -1·9 to -2·5 MHz. The shielding anisotropy for the cyanide carbon giving the highest-frequency resonance is found to be Δσ = ± 350 ppm.

ISSN:0026-8976    

DOI:10.1080/00268979600100461

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor