Correlation spectra numerical computation

With respect to the above, I note that following the publication by Froese Fischer [18] and by McCullough [19] of codes for the numerical solution of HF (or MCHF) equations for atomic and for diatomic states respectively, it has been demonstrated on prototypical unstable states (neutral, negative ion, molecular diabatic) that the state-specific computation of correlated wave-functions representing the localized component of states embedded in the continuous spectrum can be done economically and accurately, for example, [9,10,17, 20-22] and references there in. 

Appendix 8 presents some C chemical shift correlation tables with instructions. Complete C chemical shift correlation tables are too numerous to include in this book. If you are interested, consult the textbooks by Levy, Maeomber, Silverstein, and FrieboUn, which are listed in the references at the end of this chapter. Even more convenient than tables are computer programs that caleulate C chemical shifts. In the more advanced programs, the operator need only sketch the molecule on the screen, using a mouse, and the program will calculate both the chemical shifts and the rough appearance of the spectrum. Some of these programs are also listed in the references. 

An alternative way to obtain the spectral density is by numerical simulation. It is possible, at least in principle, to include the intramolecular modes in this case, although it is rarely done [198]. A standard approach [33-36,41] utilizes molecular dynamics (MD) trajectories to compute the classical real time correlation function of the reaction coordinate from which the spectral density is calculated by the cosine transformation [classical limit of Eq. (9.3)]. The correspondence between the quantum and the classical densities of states via J(co) is a key for the evaluation of the quantum rate constant, that is, one can use the quantum expression for /Cj2 with the classically computed J(co). This is true only for a purely harmonic system [199]. Real solvent modes are anharmonic, although the response may well be linear. The spectral density of the harmonic system is temperature independent. For real nonlinear systems, J co) can strongly depend on temperature [200]. Thus, in a classical simulation one cannot assess equilibrium quantum populations correctly, which may result in serious errors in the computed high-frequency part of the spectrum. Song and Marcus [37] compared the results of several simulations for water available at that time in the literature [34,201] with experimental data [190]. The comparison was not in favor of those simulations. In particular, they failed to predict... 

The CSD system is used by a broad spectrum of scientists who need to access individual crystal structures or, more commonly, want systematic information on three-dimensional (3D) structure at atomic resolution. Over the past two decades, the CSD system has provided the essential basis for experiments in structure correlation and in the rational design of novel bioactive molecules of pharmaceutical or agrochemical interest. A variety of statistical, numerical, and computational methodologies have been applied to the CSD, giving rise to the concepts of knowledge acquisition, or data mining, from... 

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