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Effective separable embedding potentials

The separable embedding potential (8.31) was apphed to model the single chemical bond between the atom A of the cluster and the atom B of the cluster environment [488]. To simulate the effect of the cluster environment the atom B is replaced by a pseudoatom Bps at the same position as the actual atom B. The influence of the pseudoatom on the cluster is described by the potential that was assumed to have the following form ... [Pg.307]

Center for Healthcare Technologies at Lawrence Livermore National Laboratory in Livermore, potentially capable to measure pH at or near the stroke site29. The probe is the distal end of a 125 pm fibre tapered up to a diameter of 50 pm. A fluorescent pH-indicator, seminaphthorhodamine-1-carboxylate, is embedded inside a silica sol-gel matrix which is fixed to the fibre tip. Excitation of the dye takes place at 533 nm and the emission in correspondence of the acid (580 nm) and basic (640 nm) bands are separately detected. The use of this ratiometric technique obviates worrying about source fluctuations, which have the same effects on the two detected signals. The pH sensor developed was first characterised in the laboratory, where it showed fast response time (of the order of tens of seconds) and an accuracy of 0.05 pH units, well below the limit of detection necessary for this clinical application (0.1 pH units). The pH sensor was also tested in vivo on rats, by placing the pH sensor in the brain of a Spraque-Dawley rat at a depth of approximately 5 mm30. [Pg.425]

This approach can be used to model non-bonded interactions in molecular mechanics instead of using empirical potentials. The rule of thumb, equation (6.6) predicts effective strain-free zero-order bond lengths. As no interaction is possible at separations larger than 2 x rc, the maximum d0(obs) for C- C is 3.70 A, and hence do = 3.70 — 0.28/4 cs 3.6A d0(C---H) 2.75 — 0.19/5 = 2.55A. The separation between non-bonded H atoms depends on the atom to which they are linked - the H ionization sphere is completely embedded within that of the larger atom. As a first approximation d0(H- H)= do(C- H) is assumed. [Pg.228]

Finally, some spectroscopic applications for pseudopotentials within SOCI methods are presented in section 3. We focus our attention on applications related to relativistic averaged and spin-orbit pseudopotentials (other effective core potentials applications are presented in chapters 6 and 7 in this book). Due to the large number of theoretical studies carried out so far, we have chosen to illustrate the different SOCI methods and discuss a few results, rather than to present an extensive review of the whole set of pseudopotential spectroscopic applications which would be less informative. Concerning the works not reported here, we refer to the exhaustive and up-to-date bibliography on relativistic molecular studies by Pyykko [21-24]. The choice of an application is made on the basis of its ability to illustrate the performances on both the pseudopotential and the SOCI methods. One has to keep in mind that it is not easy to compare objectively different pseudopotentials in use since this would require the same conditions in calculations (core definition, atomic basis set, SOCI method). The applications are separated into gas phase (section 3.1) and embedded (section 3.2) molecular applications. Even if the main purpose of this chapter is to deal with applications to molecular spectroscopy, it is of great interest to underline the importance of the spin-orbit coupling on the ground state reactivity of open-shell systems. A case study is presented in section 3.1.4. [Pg.481]

Recently introduced new separable potentials [488,490] have several kinds of ap>-plications 1) when some special region of a covalently bonded sohd or very large molecule is modeled by a modest-sized cluster, each dangling bond at the cluster surface can be saturated in a way that exactly reproduces the bond in the complete system 2) a similar approach can be used at the matching surface in an embedding scheme for calculations on the same type of systems 3) application to atomic effective core potentials where the new potential operator avoids the possibility of ghost states that sometimes plague the widely used pseudopotentials. [Pg.305]

In recent years it has become necessary to develope techniques to ensure the safety of computer embedded systems controlling potentially dangerous processes. Some works published last years showed that reliability and safety improvements could be achieved by using FTA 4,5 and FMEA 6 (Failure Mode and Effect Analysis) techniques. This paper attemts to apply and evaluate the FTA method in a software embedded system. Such an application will enable the safety engineer to use one method for the system as a whole without separating the software from the hardware. [Pg.86]


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See also in sourсe #XX -- [ Pg.305 ]




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