Response function theory

In Sections III—VI the nuclear displacement operators H n) are treated as perturbation operators and response function theory is used to determine the implicit geometry dependence of the wave function to each order in the nuclear displacement ... 

To date, not much use has been made of the MCSCF based EOM theories as developed in the author s group. Instead, the framework of time-dependent response theory, which can treat essentially any kind of reference wave function l0,A ) including the MCSCF variety, has superceded the EOM-based developments for such cases. It is important to keep in mind, however, that both the EOM and response function theories involve formulating and solving sets of equations whose solution (i.e. the unknown energy) is an intensive energy. 

A good overview of time-dependent response function theory, including linear and non-linear response functions is offered in J. Olsen and P. Jprgensen, Time-dependent response theory with applications to self-consistent field and multiconfigurational self-consistent field wave functions, in D. Yarkony (Ed.), Modern electronic structure theory. World Scientific Publishing, Singapore, 1995, pp. 857-990. 

The aim of this book is to present the basic aspects of the molecular response function theory for molecular systems in solution described with the Polarizable Continuum Model, giving special emphasis both to the physical basis of the theory and to its quantum chemical formalism. The QM formalism will be presented in the form of the coupled-cluster theory, as it is the most recent and less known formulation for the QM calculation of molecular properties within the PCM... 

The response functions theory the PCM method [1] is an extension of the response theory for molecules in the gas phase [2, 3], This latter is based on a variational-perturbation approach for the description of the variations of the electronic wave function and of the changes of the observables properties at the various orders of perturbation with respect to the perturbing fields, and no restrictions are posed on the nature of the observables and on the nature of the perturbing fields, and the theory gives also access to a direct determination of the transition properties (i.e. transition energies and transition probabilities) associated with transitions between the stationary states of the molecular systems. The PCM response theory adds to this framework several new elements. 

The PCM response function theory has been developed for linear and non-linear response functions and at several QM levels, including the variational wavefimctions methods (SCF,MCSCF) and the Density Functional Theory [4-18] and more recently at the Coupled-Cluster level [19, 20]. 

RESPONSE FUNCTION THEORY COMPUTATIONAL APPROACHES TO LINEAR AND NONLINEAR OPTICAL SPECTROSCOPY... 

One of the main objectives of response function theory (RFT) [1-5] has from the beginning been the calculation of spectroscopic properties. RFT can be regarded as a convenient way to reformulate time-dependent perturbation theory [6] to a form where it is particularly well suited for parametrization and implementation within approximate wavefunction/density-based approaches. RFT provides a recipe for computing the response of a given (molecular) system to an external, time-dependent perturbation... 

---