Dispersion coefficients component expansion

A sum-over-states expression for the coefficient A for the expansion of the diagonal components faaaa was derived by Bishop and De Kee [20] and calculations were reported for the atoms H and He. However, the usual approach to calculate dispersion coefficients for many-electron systems by means of ab initio response methods is still to extract these coefficients from a polynomial fit to pointwise calculated frequency-dependent hyperpolarizabiiities. Despite the inefficiency and the numerical difficulties of such an approach [16,21], no ab initio implementation has yet been reported for analytic dispersion coefficients for frequency-dependent second hyperpolarizabiiities which is applicable to many-electron systems. 

As was proven later by Bishop [19], the coefficient A in the expansion (73) is the same for all optical processes. If the expansion (73) is extended to fourth-order [4,19] by adding the term the coefficient B is the same for the dc-Kerr effect and for electric field induced second-harmonic generation, but other fourth powers of the frequencies than are in general needed to represent the frequency-dependence of 7 with process-independent dispersion coefficients [19]. Bishop and De Kee [20] proposed recently for the all-diagonal components yaaaa the expansion... 

The anode disperses the fuel gas over its surface, where active sites promotes the oxidation of the fuel, and conducts the electrons to the external circuit. Thus, the material used on the anode must be stable in the reducing environment of the fuel, electronically conducting and have sufficient porosity to allow transport of gases [3]. Cermets of Ni-YSZ are commonly used as anodes, where Ni provides the electrical conductivity and YSZ inhibits the coarsening of the Ni particles and provides a thermal expansion coefficient close to those of the other cell components [1]. 

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