Multidetermination example

An ANN is a systematic procedure for data processing inspired by the nervous system function in animals. It tries to reproduce the brain logical operation using a collection of neuron-like entities to perform processing of input data. Furthermore, it is an example of a connectionist model, in which many small logical units are connected in a network [52]. Let us consider the proposed case, a multidetermination application employing an array of ISEs as input data. In a rather complex system,... 

Configuration interaction treatments can also be easily extended to multideterminant problems but these require even more care and an exorbitant computational effort [15]. Multi-reference Cl approaches are ideally suited to determining, for example, electronic spectra, as they can deal with excited states in a straightforward fashion [16]. 

Although a spin-orbital formulation is conceptually simple, desirable properties such as spin-adaptation may be lost when the electronic state of interest is open shell, for example. A rigorously spin-adapted theory must include spin-free definitions of the cluster operators, T, and an appropriate (perhaps multideterminant) reference wavefunction (Refs. 39, 41, 42, 156-158). Such general coupled cluster derivations are beyond the scope of this chapter, though some of the issues associated with difficult open-shell problems are discussed in the next section. 

Multideterminations involving solid samples Determinations of this type using pervaporation have so far focused on speciation analysis [181]. The two most salient examples reported to date are the speciation of inorganic and organic forms of mercury (Fig. 4.23A) and that of nitrogen as ammonia and urea (Fig. 4.23B). 

An example of simultaneous multidetermination executed via a single injection and employing several detectors has in fact already been mentioned in Section 4.1, where the simultaneous determination of pH and pCa [21] was presented (Fig. 4.4). Another similar application is the scheme presented by Virtanen [250] for the determination of Na, K", Ca ", and Cl in serum by the use of ion-selective electrodes in which system the flow impinged laterally on both the sensors and the reference electrode, which was located behind them and in the same position, an... 

The nodal surface is independent of the Jastrow correlation factor which therefore determines only the efficiency of the calculation, not the accuracy. High accuracy is already obtained for many systems with one Slater determinant, often built from Kohn-Sham orbitals. For many years, multideterminant wave functions have been employed which are necessary for high accuracy in systems with non-dynamical correlation. Recent examples are papers by Caffarel and coworkers where large complete active spaces have been used." " These authors emphasize the importance of systematic cancellation of the node location error which can be achieved with CASSCF-type wave functions. While full CASSCF wave... 

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