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Contact transformation perturbation operator

In this section, we shall use the degenerate perturbation theory approach to derive the form of the effective Hamiltonian for a diatomic molecule in a given electronic state. Exactly the same result can be obtained by use of the Van Vleck or contact transformations [12, 13]. The general expression for the operator up to fourth order in perturbation theory is given in equation (7.43). Fourth order can be considered as the practical limit to this type of approach. Indeed, even its implementation is very laborious and has only been used to investigate the form of certain special terms in the effective Hamiltonian. We shall consider some of these terms later in this chapter. For the moment we confine our attention to first- and second-order effects only. [Pg.316]

The use of van Vleck s contact transformation method for the study of time-dependent interactions in solid-state NMR by Floquet theory has been proposed. Floquet theory has been used for studying the spin dynamics of MAS NMR experiments. The contact transformation method is an operator method in time-independent perturbation theory and has been used to obtain effective Hamiltonians in molecular spectroscopy. This has been combined with Floquet theory to study the dynamics of a dipolar coupled spin (I = 1/2) system. [Pg.226]


See other pages where Contact transformation perturbation operator is mentioned: [Pg.228]    [Pg.228]    [Pg.511]    [Pg.619]    [Pg.117]    [Pg.139]    [Pg.172]    [Pg.139]    [Pg.606]    [Pg.619]    [Pg.21]    [Pg.437]   
See also in sourсe #XX -- [ Pg.228 ]




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