Hydrogen atoms, chemical potential

Figure 42 (from the chapter Nonadiabatic Chemical Dynamics ) The potential energy contour felt by a hydrogen atom when the two atoms N (left side) and C (right side) are fixed. 

To make contact with atomic theories of the binding of interstitial hydrogen in silicon, and to extrapolate the solubility to lower temperatures, some thermodynamic analysis of these data is needed a convenient procedure is that of Johnson, etal. (1986). As we have seen in Section II. l,Eqs. (2) et seq., the equilibrium concentration of any interstitial species is determined by the concentration of possible sites for this species, the vibrational partition function for each occupied site, and the difference between the chemical potential p, of the hydrogen and the ground state energy E0 on this type of site. In equilibrium with external H2 gas, /x is accurately known from thermochemical tables for the latter. A convenient source is the... 

Although Dirac s equation does not directly admit of a completely self-consistent single-particle interpretation, such an interpretation is physically acceptable and of practical use, provided the potential varies little over distances of the order of the Compton wavelength (h/mc) of the particle in question. It allows, for instance, first-order relativistic corrections to the spectrum of the hydrogen atom and to the core-level densities of many-electron atoms. The latter aspect is of special chemical importance. The required calculations are invariably numerical in nature and this eliminates the need to investigate central-field solutions in the same detail as for Schrodinger s equation. A brief outline suffices. 

In further support of the notion of electronic tautomerism, Fry cited the 1905 paper by E. C. C. Baly and C. H. Desch in which they described ketoenol tautomerism as the result of the motions of a labile hydrogen atom that functions as a potential ion, "inasmuch as the bond of attraction or Faraday tube of force must be considered to be lengthened sufficiently to allow the interchange of the atom from the one position to the other within the molecule." Thus, the difference between "electrolytes" (electrical molecules) and nonelectrolytes (chemical molecules) has to do with conditions that determine the varying lengths of the Faraday tubes. 125 Baly and Desch s hypothesis was a result of their rumination on Wislicenus s earlier hypothesis (i.e., that the influence of "electrochemical polarization" explains the acidic properties of acetoacetic ester) in combination with thinking about J. J. Thomson s ideas. 126... 

---