Allen configurational energies

More recently, in 1989, Allen developed his spectroscopic scale, xs, where he equated the electronegativity of an atom to its configuration energy (CE)... 

More recently Allen has proposed that electronegativity be defined in terms of the average one-electron energy of valence shell electrons in ground-state free atoms which may be obtained spectroscopically. This quantity is termed the configuration energy ... 

TABLE 5.12 Electronegativities of selected elements using the revised Pauling scale, the Mulliken-Jaffe scale, and Allen s spectroscopic configuration energies. The iatter scales have been converted to the revised Pauling scale. The Mulliken-Jaffe values are listed for the sp valence hybridization, uniess otherwise indicated. 

A key configuration in these water clusters, in ice and in clathrate hydrates is the pentamer (Fig. 4) in which one water molecule at the centre of a tetrahedron is hydrogen-bonded to four other water molecules at the vertices. Here two hydrogen bonds are formed by H-transfer and two by electron transfer . The calculated average bond energy is similar to that for the dimer (Kollmann and Allen, 1970 Hoyland and Kier, 1969). More sophisticated calculations on... 

Generally, MD is performed to simulate a continuous phase trajectory in the microcanonical N,E,V) ensemble, while in MC method, individual phase points of an (N,V,T) ensemble are simulated. As far as the equilibrium properties are concerned, the trajectory average of MD and the configurational average of MC are equivalent (Allen and Tildesley, 1987). Recently, MD simulation of other types of ensembles also have been achieved. In the N,E,V) simulations, volume and total energy are held constant and the temperature and pressure are allowed to fluctuate. Andersen (1980) suggested methods for simulation of isobaric-isoenthalpic and isobaric-isothermal (A, P,7) ensembles. A... 

T. J. Lee, W. D. Allen, and H. F. Schaefer, III, J. Chem. Phys., 87, 7063 (1987). The Analytic Evaluation of Energy First Derivatives for Two-Configuration Self-Consistent Field Configuration Interaction Wavefunctions. Applications to Ozone and Ethylene. 

An alternative to molecular dynamics based simulated annealing is provided by Metropolis importance sampling Monte Carlo (Metropolis et al., 1953) which has been widely exploited in the evaluation of configurational integrals (Ciccotti et al., 1987) and in simulations of the physical properties of liquids and solids (Allen and Tildesley, 1987). Here, as outlined in Chapters 1 and 2, a particle or variable is selected at random and displaced both the direction and magnitude of the applied displacement within standard bounds are randomly selected. The energy of this new state, new, is evaluated and the state accepted if it satisfies either of the following criteria ... 

Allen [3] has defined the mean valence shell ionization energy or MIF of an atom as the weighted mean of the configuration-averaged ionization energies of valence shell 5 and p electrons ... 

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