Zobrazeno 1 - 10
of 129
pro vyhledávání: '"K. W. H. Stevens"'
Autor:
K. W. H. Stevens
Publikováno v:
Czechoslovak Journal of Physics. 50:1059-1074
A generic Hamiltonian, which contains the potential energies and the coulomb interactions of an assembly of N4He nuclei and 2N electrons is studied using second quantisation techniques and different sets of boundary conditions for three related probl
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::2ac5c6f3db709c7dee72decbe25e47e7
https://doi.org/10.1023/a:1022835519935
https://doi.org/10.1023/a:1022835519935
Autor:
K. W. H. Stevens
Publikováno v:
Czechoslovak Journal of Physics. 41:819-824
The symmetry of the antiferromagnetic Heisenberg exchange interaction is lowered by dipolartype interactions. It is reasoned that the combination of small transition matrix elements and the “zero field” splittings due to the symmetry lowering can
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::aef420ebe0b1fd43dec7139ed717a57e
https://doi.org/10.1007/bf01599687
https://doi.org/10.1007/bf01599687
Autor:
K W H Stevens
Publikováno v:
Journal of Physics: Condensed Matter. 2:10085-10090
The author attempts to determine how much of the Ising ground state there is in the ground state of an Heisenberg antiferromagnetic. Square planar clusters of 5, 13 and 25 spins of 1/2 are considered, using approximate ground states chosen as a resul
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::a87e1c99c0dce87ba0c06e0b4364a992
https://doi.org/10.1088/0953-8984/2/50/013
https://doi.org/10.1088/0953-8984/2/50/013
Autor:
K W H Stevens, C L Foden
Publikováno v:
Journal of Physics: Condensed Matter. 2:5179-5190
The energy levels of a double-quantum-well system can be expected to occur in closely spaced pairs, due to 'tunnelling', so raising the possibility that oscillations can occur at the tunnelling frequencies. This paper gives a detailed theory of the e
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::2f8f26538f9bb1276dd1fccbb1d36caa
https://doi.org/10.1088/0953-8984/2/23/008
https://doi.org/10.1088/0953-8984/2/23/008
Autor:
K W H Stevens, J H Jefferson
Publikováno v:
Journal of Physics C: Solid State Physics. 9:2151-2165
Using thermodynamic perturbation theory the statistical mechanics of intermediate-valence rare earth compounds is investigated. The Gibbs' free energy is calculated to second order in the Anderson mixing interaction and is shown to diverge logarithmi
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::c3f2199cb8d63ce4fbbd85731ced65fe
https://doi.org/10.1088/0022-3719/9/11/021
https://doi.org/10.1088/0022-3719/9/11/021
Autor:
F Mehran, K W H Stevens
Publikováno v:
Journal of Physics C: Solid State Physics. 20:5773-5789
A theory of spin-resonance lineshapes in random magnetic compounds is developed and applied to the insulating Heisenberg system EuxSr1-xS. The magnetic dipolar interaction is treated as a perturbation on the unperturbed Hamiltonian consisting of exch
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::329a0ec13e6993c91f9d75e9f0748420
https://doi.org/10.1088/0022-3719/20/34/014
https://doi.org/10.1088/0022-3719/20/34/014
Autor:
K W H Stevens, M Roberts
Publikováno v:
Journal of Physics C: Solid State Physics. 13:5941-5955
An approximate contraction is defined which enables the perturbation series for the intermediate valence model to be summed to all orders. Two forms of Coulomb correlation, U, are considered and in both cases it is demonstrated that the Fermi level a
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::30e088cfd4f7670aa621ac07af47104e
https://doi.org/10.1088/0022-3719/13/32/017
https://doi.org/10.1088/0022-3719/13/32/017
Publikováno v:
Journal of Physics C: Solid State Physics. 9:1511-1520
The form of the exchange interaction between two Co2+ ions, each at a site having octahedral symmetry, is derived using the formalisms of second-quantisation and double-tensor operators. Both first-order contributions, from the two-particle spin-inde
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::b53541e2f2afe76b8214aea0333dc872
https://doi.org/10.1088/0022-3719/9/8/022
https://doi.org/10.1088/0022-3719/9/8/022
Autor:
K. W. H. Stevens
Publikováno v:
Canadian Journal of Physics. 63:50-53
The free and hindered rotation in a plane of a methyl group has recently been studied. Although the theory has been in existence for some time, errors were found in it. A similar theory exists for the rotation of methane, in three dimensions. It is d
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::13e045eaa098420337d73d79b1b8b757
https://doi.org/10.1139/p85-008
https://doi.org/10.1139/p85-008