Correlation of Zeno line with acentric factor and other properties of normal fluids

Abstract

The Coulomb hole reduces this repulsion and gives rise to a smaller net energy of the triplet. A£def(uCHF) and AE^rCHF) are very similar and much smaller than A£def(aiPI). In consequence, we obtain a smaller transition energy after correlation: 20.1-20.3 eV at the observed geometry.The correlation correction has reduced the aiPI error for this transition, at the observed geometry, from 14.8 to 2.72 eV. Moreover, the connection between the crystal and free-atom transition is much more sensible after inclusion of electron correlation (Figure 6): the crystal calculation at 11 bohr must be very close to the free-atom value, given the negligible neon-neon interactions at such distance. The residual error found in the rCHF spectral calculation may well be a measure of the shortcomings of our rigid model, defined in terms of a single-atom excitation taking place in an unrelaxed ground-state lattice.According to this work, the *S -* 3P transition energy increases with pressure up to 60 GPa. A similar result was found by LeSar for solid argon.10 VI. ConclusionsWe have shown that the ab initio perturbed ion method, initially designed to study ionic systems,12•13,17 can describe simple van der Waals systems such as solid neon. The pseudoatomic character of the aiPI method suggests a simple and intuitive analysis of the lattice stabilization, showing the relative importance of different orbitals and different terms in the Hamiltonian. The aiPI method can also be a very useful tool as generator of (a) atomic wave functions consistent with its lattice environment, and (b) local effective potentials for different atoms in the lattice. This information may be a sensible input for more involved molecularcluster calculations.The following conclusions can be drawn from our calculation:1. The aiPI method predicts the binding energy and the equilibrium lattice parameter of fee neon in agreement with experimental information.2. For small lattice sizes the crystal electron density is contracted with respect to the gas-phase density. This effect is mostly due to the 2p atomic orbital, the Is and 2s orbitals playing a negligible role.3. The crystal stabilization may be understood in terms of two pure quantum-mechanical effects: the long-range, attractive exchange interaction and the short-range lattice-projection energy representing the atom-lattice orthogonality.4. It appears that the Is and 2s electron densities act as stabilizing factors whereas the 2p density slightly destabilizes the crystal.5. The 2p -3s instantaneous absorption has been studiedwithin the aiPI method in terms of an excited atom embedded in the ground-state crystal. A new interpretation is given for the energy shift with respect to the gas-phase absorption, in terms of deformation and interaction energies of the two states involved in the transition. The analysis reveals the importance of electron correlation effects in the excited state, originating from the large crystal-induced compression of the 3s state. This transition seems to increase with increasing ext...

Deriving Analytical Expressions for the Ideal Curves and Using the Curves to Obtain the Temperature Dependence of Equation-of-State Parameters

“…During the late 1960s, Holleran [6][7][8][9] proposed several useful applications for the Z = 1 contour. In recent years, from molecular-dynamics simulations, Herschbach [5] obtained a Zeno line close to experimentally measured values over a wide range of densities by using the Lennard-Jones potential, simple point charge (SPC), and extended SPC (SPC/E) models for pure water.…”

“…The Z = 1 contour was first discovered by Batchinski [4] in 1906. Among the diverse names used are the orthometric condition, ideal-gas curve, and finally the term Zeno line was adopted by Xu and Herschbach [5]. During the late 1960s, Holleran [6][7][8][9] proposed several useful applications for the Z = 1 contour.…”

Calculations of the direct electromagnetic enhancement in surface enhanced Raman scattering on random self-affine fractal metal surfaces

“…A similar EM enhancement is assumed to occur at the Raman-shifted frequencies, which combined with the former direct enhancement may give rise to an overall FE factor on the order of or above 10 4 . A SPP can be either propagating along a continuous surface [12][13][14][15][16] ͑extended SPP͒, confined within metal particles ͑particle plasmon resonances, 5,6,[17][18][19]21 ͒ or even localized due to Anderson localization 15,[22][23][24] ͑localized SPP͒; of course, some of these effects may take place altogether on real SERS metal substrates. It is interesting to note that most of the numerous theoretical works devoted to the description of the EM mechanism, from the subsequent papers following SERS first reports ͑cf.…”

Near-field electromagnetic wave scattering from random self-affine fractal metal surfaces: Spectral dependence of local field enhancements and their statistics in connection with surface-enhanced Raman scattering

“…In recent years, the theoretical efforts have been directed towards either describing through approximate methods realistic surface models, 8,10,13,[22][23][24] or using the full EM theory to study simplistic surface models, [25][26][27] though introducing increasingly complex properties. 26,27 In this paper we study the near EM field scattered in the vicinity of rough, one-dimensional self-affine fractal surfaces of Ag, Au, and Cu, with the aim of determining the appearance of strong local optical excitations (hot spots) and characterizing them with regard to their spatial and spectral width, their polarization, and their excitation spectra; in addition to that, the global optical response of such fractal surfaces will be studied through the statistical properties of the surface EM fields.…”