The simplest model of the condensed phase is represented by the lattice-gas model [50]. It reflects two major features of the any species in the condensed phase, viz., their characteristic volume and species interactions. The volume of a crystalline solid is characterized by its natural lattice. With a good approximation, one can consider that the subsurface region of a solid is [Pg.357]

To describe the experimental observation [40] of the solid condensed - liquid expanded phase transitions in brush-like monolayers on silica gel a simple lattice model and the theory of orientational effects in adsorbed monolayers were used [36-38]. It was assumed that interaction between the n-octadecanol molecule and the solid could be presented as [Pg.510]

One final solid phase calculation is a study by Shin of diatomic relaxation in condensed phases, which includes ideas from binary collision, cell model, and multiphonon relaxation theories. He calculated the energy transferred both to oscillatory motion of the surrounding lattice atoms and to the oscillations of the molecule itself. [Pg.506]

This paper presents studies of solid state polymerization aimed towards formulating a dynamic model of reactivity in the condensed phase. Phonon spectroscopy is successfully used to elucidate the mechanism of lattice control of the reaction. Novel concepts of phonon-assisted thermal and photochemical reactions are introduced, supported by experimental data. Non-linear laser spectroscopy is used to find the importance of biexcitonic processes in photopolymerization. Also, spectroscopic studies of reactions in Langmuir-Blodgett films and at gas-solid interface which produce ordered polymers are presented. [Pg.106]

The book covers a variety of questions related to orientational mobility of polar and nonpolar molecules in condensed phases, including orientational states and phase transitions in low-dimensional lattice systems and the theory of molecular vibrations interacting both with each other and with a solid-state heat bath. Special attention is given to simple models which permit analytical solutions and provide a qualitative insight into physical phenomena. [Pg.209]

The theoretical calculation of the thermodynamic properties of condensed phases is still in an early stage of development and only the simplest models can be treated quantitatively. For solids the simplest useful theory, that of Debye, assumes that the distribution of vibration frequencies among the atoms in the solid is the same as that of the frequencies of vibration of a continuous medium. The errors introduced by this hypothesis are difficult to estimate. Some progress has, however, been made recently in the direct evaluation of the thermodynamic properties of crystal lattices without having to liken them to continuous media.f [Pg.166]

The commonly accepted pulsar model is a neutron star of about one solar mass and a radius of the order of ten kilometers. A neutron star consists of a crust, which is about 1 km thick, and a high-density core. In the crust free neutrons and electrons coexist with a lattice of nuclei. The star s core consists mainly of neutrons and a few percents of protons and electrons. The central part of the core may contain some exotic states of matter, such as quark matter or a pion condensate. Inner parts of a neutron star cool up to temperatures 108iT in a few days after the star is formed. These temperatures are less than the critical temperatures Tc for the superfluid phase transitions of neutrons and protons. Thus, the neutrons in the star s crust and the core from a superfluid, while the protons in the core form a superconductor. The rotation of a neutron superfluid is achieved by means of an array of quantized vortices, each carrying a quantum of vorticity [Pg.45]

The traditional apparatus of statistical physics employed to construct models of physico-chemical processes is the method of calculating the partition function [17,19,26]. The alternative method of correlation functions or distribution functions [75] is more flexible. It is now the main method in the theory of the condensed state both for solid and liquid phases [76,77]. This method has also found an application for lattice systems [78,79]. A new variant of the method of correlation functions - the cluster approach was treated in the book [80]. The cluster approach provides a procedure for the self-consistent calculation of the complete set of probabilities of particle configurations on a cluster being considered. This makes it possible to take account of the local inhomogeneities of a lattice in the equilibrium and non-equilibrium states of a system of interacting particles. In this section the kinetic equations for wide atomic-molecular processes within the gas-solid systems were constructed. [Pg.370]

To this date, no stable simulation methods are known which are successful at obtaining quantum dynamical properties of arbitrary many-particle systems over long times. However, significant progress has been made recently in the special case where a low-dimensional nonlinear system is coupled to a dissipative bath of harmonic oscillators. The system-bath model can often provide a realistic description of the effects of common condensed phase environments on the observable dynamics of the microscopic system of interest. A typical example is that of an impurity in a crystalline solid, where the harmonic bath arises naturally from the small-amplitude lattice vibrations. The harmonic picture is often relevant even in situations where the motion of individual solvent atoms is very anhaimonic in such cases validity of the linear response approximation can lead to Gaussian behavior of appropriate effective modes by virtue of the central limit theorem. [Pg.2024]

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