摘要:

A grand canonical ensemble Monte Carlo method is developed for application to electrolyte solutions.

ISSN:0026-8976    

DOI:10.1080/00268978000100891

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The zeroth-order theory of intermolecular forces is used to derive additivity relations for rotationally averaged molecular dipole properties and dispersion energy constants by assuming that a molecule is comprised of non-interacting atoms or molecules. Some of the additivity rules are new and others, for example the mixture rule for dipole oscillator strength distributions (DOSDs), Bragg's rule for stopping cross sections and Landolt's rule for molecular refractivities, are well known. The additivity rules are tested by using previously constructed DOSDs and reliable values for the dipole oscillator strength sumsSk,LkandIk, and dispersion energy constantsC6, for H, N, O, H2, N2, O2, NO, N2O, NH3and H2O as models. It is found that additivity is generally unreliable for estimating molecular properties corresponding tok< -2. Generally fork≥ -2 and forC6, and if the hydrogen molecule is used to represent the hydrogen atom in the additivity rules, the additivity relations yield results that are reliable to within ⪅20 per cent and the estimates improve substantially askincreases. The effects of molecule formation on DOSDs is examined by comparing the various molecular DOSDs with the sum of the DOSDs for the atoms making up the molecules. Molecule formation results in a net decrease in the amount of dipole oscillator strength for low excitation energies and a compensating net increase for higher energies in a region extending from the absorption threshold to about 100 eV. This is shown to imply that estimates of the stopping average energyI0, obtained by usingbona fide atomic I0values, are lower bounds to the correct molecularI0results.

ISSN:0026-8976    

DOI:10.1080/00268978000100901

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The results of ENDOR investigations of magnetically dilute single crystals of Ag(II) and Cu(II) tetraphenylporphyrins (TPP) are presented and discussed. The complete hyperfine tensors, and quadrupole tensor for nitrogen, have been determined for the metal ions, nitrogens and pyrrole protons. The non-first order14N ENDOR spectra resulting from multiple equivalences among the nitrogen nuclei have been completely analysed by exact diagonalization.

ISSN:0026-8976    

DOI:10.1080/00268978000100911

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Inelastic scattering cross sections for collisions of electrons with helium atoms in metastable 21,3Sstates are calculated for some final states ofSandPsymmetry by using the First Born Approximation and the Random Phase Approximation. The results for the total cross sections compare reasonably well with previous accurate values in the case of singlet-singlet transitions.

ISSN:0026-8976    

DOI:10.1080/00268978000100921

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The HeI photoelectron spectrum of the NH2(X2B1) radical produced from the rapid reaction

ISSN:0026-8976    

DOI:10.1080/00268978000100931

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

We study the effect of the anharmonicity of a normal diatomic moleculeBCon the vibrational predissociation rates of a van der Waals moleculeX…BC, whereXis a rare-gas atom. The experimentally determined nonlinear dependence of vibrational predissociation rates of the HeI2(B) molecule on the vibrational excitation of the I2bond, is very well reproduced by a simple analytical model. The relevance of this model in determining potential parameters of the van der Waals interaction is discussed. Application to other systems are presented and the effect of the reduced mass for relative motion is examined.

ISSN:0026-8976    

DOI:10.1080/00268978000100941

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The crystal structure of a 1 : 1 stoichiometric adduct of urea and malonic acid, has been investigated in connection with an ENDOR study of the paramagnetic centre which is formed by γ-irradiation of a single crystal. It is found that the crystal structure consists of a two-dimensional network of hydrogen bonded urea and malonic acid molecules. Interesting features are the planarity of the acid molecule induced by the presence of an intramolecular hydrogen bond, and the presence of a very short hydrogen bond between the carboxylic group and an urea molecule. The position of the proton in this bond is discussed.

ISSN:0026-8976    

DOI:10.1080/00268978000100951

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The ENDOR spectra of γ-irradiated single crystals of the urea-malonic acid 1 : 1 adduct were recorded at room temperature. The hyperfine coupling tensor of the α proton of the HOOC-CH-COOH free radical formed by irradiation were measured as well as the hyperfine coupling tensors of a number of hydrogen bonded protons. The tensor elements are compared with values calculated according to the McConnell and Strathdee procedure taking into account the spin distribution in a π- orbital extending over the whole molecule. The position of the proton belonging to a very short hydrogen bond is discussed on the basis of its dipolar and isotropic interaction.

ISSN:0026-8976    

DOI:10.1080/00268978000100961

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The triple-dipole term in the non-additive three body contributions to the 0 K lattice energy has been evaluated for systems of axially symmetric molecules crystallizing in the f.c.c. (α-N2) lattice structure. Stogryn's expressions for the triple-dipole energy of non-spherical molecules were used in lattice summations over 24 shells of neighbours. For α-N2and CO2these results were used to estimate the associated non-additive energy, which was found to be significant, about 6 per cent of the experimental sublimation energy in each case, but the effect of the molecular anisotropy on the triple-dipole energy was found to be quite small.

ISSN:0026-8976    

DOI:10.1080/00268978000100971

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The mean squared force in a general molecular liquid is developed in terms of the spherical harmonic expansion of the interaction energy of two molecules. The convergence of this series is examined by calculating the mean squared force and the expansion coefficients in a molecular dynamics simulation. For site-site intermolecular potentials (ISM or interaction site models), the mean squared force can be calculated in terms of the angle-averaged site-site distribution functions (gαγ(rαγ≡g000αγ(rαγ). The mean squared torque for an ISM fluid can be calculated from a knowledge ofg000αγ(rαγ) plus the angular correlations contained in the two higher harmonic coefficients,g100αγ(rαγ) andg200αγ(rαγ). These three coefficients are calculated in molecular dynamics simulations of ISM fluids representing liquid nitrogen and liquid chlorine and their usefulness in calculating the mean squared torque is demonstrated. The calculation of multipolar contributions to the thermodynamic and quasithermodynamic properties of ISM fluids is briefly discussed.

ISSN:0026-8976    

DOI:10.1080/00268978000100981

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor