Rayleigh-Schrodinger perturbation response theory

Formalism of the so-called response theory is another, quite universal language for the description of the more general approach to Rayleigh-Schrodinger perturbation theory suggested above, in which the summation over excited states is effectively replaced with solving a large system of linear equa-... [Pg.128]

Often, only the linear or quadratic response of the unperturbed system to the perturbation X is required (the perturbative approach is often also denoted as response theory). In other words, we have to calculate the lowest-order corrections of stationary Rayleigh-Schrodinger perturbation theory for... [Pg.570]

A Rayleigh-Schrodinger-type perturbation theory has recently been developed by Angyan [107], The consideration of external perturbations, like electric fields, permits the calculation of response functions for solvated species. [Pg.298]