摘要:

The isotope shifts in the isotropic hyperfine coupling constants of certain isotopically substituted methyl radicals are evaluated from vibronic wave functions in the Born-Oppenheimer approximation, with the electronic wave function calculated via self-consistent field molecular orbital theory with the INDO approximations for atomic and molecular integrals. The theory at this level of approximation is found to accommodate quite well the trends in the experimentally observed quantities, and to provide a basis for a discussion of the reasons for the observed trends in terms of the orbital description of electronic structure.

ISSN:0026-8976    

DOI:10.1080/00268976800100511

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The theory of Prigogine is applied to the deduction of the molecular structure of a simple dense fluid not in equilibrium, described in terms of the phase singlet distribution. The intermolecular interaction is assumed to have the form of the sum of constituent pair forces, and the pair force itself is supposed to be composed of a hard core and an extended weak interaction. It is shown how the Rice-Allnatt equation can be derived in this way, but that the natural development of the theory of the time evolution of the singlet distribution is such as to lead as a first approximation to the equation recently given independently by Popielowski, Rice and Hurt. An improved equation for the singlet distribution is derived, in § 8, and some comments are made about the present standing of the theory in its application to dense fluids.

ISSN:0026-8976    

DOI:10.1080/00268976800100521

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The Dirac equation for the electron is solved to terms that are second order in the applied field by the application of the Foldy-Wouthuysen transformation. In the process this generates all the terms that are necessary to ensure that thegtensor is gauge-invariant to the third order. An explicit expression is given for the third-ordergtensor and the result is compared with the formula given by Tippins [1]. A term that reflects the velocity dependence by the Bohr magneton gives a significant contribution especially for atoms of high atomic number. This same term is additional to the extra term obtained by Stone [2] and is of the same magnitude: it must be invoked to account for thegfactor of atomic hydrogen.

ISSN:0026-8976    

DOI:10.1080/00268976800100531

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

General valence force field constants for NF3have been calculated using very accurate frequency data, Coriolis coupling constants (ζ) and centrifugal distortion constants. The calculated constants are in excellent agreement with the experimental ones. Mean amplitudes of vibration were also calculated by some different methods, and thermodynamic functions are given for the temperature range 200 to 2000°k. Earlier investigations of these molecular constants are less accurate or incorrect.

ISSN:0026-8976    

DOI:10.1080/00268976800100541

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

La comparaison des intensités de signaux de résonance paramagnétique électronique de solutions de biradicaux à échange interélectronique faible, fort ou intermédiaire, montre que le téréphthalate est un biradical à échange faible.

ISSN:0026-8976    

DOI:10.1080/00268976800100551

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The multi-configuration self-consistent field operator is derived. We then transform the orbitals into an orthonormal set and obtain pseudo-eigenvalue equations. Possible applications of these equations are discussed.

ISSN:0026-8976    

DOI:10.1080/00268976800100561

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The general expression for the magnetic-field-induced quadrupole splitting is derived fordntransition metal ions in a crystal field of octahedral symmetry. The effective magnetic field may arise from either an applied field or a molecular field. Bonding effects are also treated. The temperature dependence of the quadrupole splitting ΔEQinduced by an applied magnetic field is calculated for57Fe high-spin ferrous and low-spin ferric compounds where the ions are in crystal fields of octahedral symmetry.

ISSN:0026-8976    

DOI:10.1080/00268976800100571

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The direct method of analysis is applied to the spectra of oriented molecules with two and three spins.

ISSN:0026-8976    

DOI:10.1080/00268976800100581

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A normal-coordinate treatment has been carried out for CH2O, CHDO, and CD2O in the1A2excited state using the most general quadratic potential function of the valence force type and employing a perturbation programme. Using the available data for the three isotopic molecules, a set of force constants was calculated, five unobserved frequencies were predicted and one reported frequency was corrected. The reliability of the predicted values was checked using the product rule and the sum rule for the isotopic species.

ISSN:0026-8976    

DOI:10.1080/00268976800100591

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The nuclear spin-spin coupling constants in methane, cthane, ethylene and acetylene are calculated using the Ramsey perturbation formalism. SCF MO's determined by the CNDO method are used to construct the ground state and all singly-excited triplet states. The coupling constants with and without configuration interaction between the triplet states are compared with independent electron calculations, full SCF calculations and experiment. The results show considerable improvement over those obtained by independent electron methods and are in reasonable agreement with experiment and the full SCF calculations.

ISSN:0026-8976    

DOI:10.1080/00268976800100601

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor