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Spin‐free quantum chemistry. XVI. Spin correlation
Author(s) -
Matsen F. A.,
Welsher T. L.
Publication year - 1975
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560090117
Subject(s) - hamiltonian (control theory) , correlation function (quantum field theory) , scattering , neutron scattering , quantum mechanics , spin (aerodynamics) , physics , condensed matter physics , operator (biology) , chemistry , thermodynamics , mathematics , mathematical optimization , biochemistry , repressor , gene , transcription factor , dielectric
We discuss the calculation of quasielastic critical neutron scattering for systems defined by a spin‐free Hamiltonian. The system dependent property which determines the critical scattering is the thermal average of a spin‐free operator called the general unpaired electron correlation operator. For localized models, we obtain the scattering as the Fourier transform of an unpaired site correlation function. The algebraic relationship between this correlation function and the usual spin correlation function is discussed as are its relationships to thermodynamic properties. Correlations in the infinite interaction range model, linear spin wave model, and infinite chain Heisenberg model are given. In the last case, an estimate of the low temperature correlation length is made.