Liquid structure density-functional theories

Figure 6 Singly occupied molecular orbital (SOMO) of a propeller-like trimer radical anion of acetonitrile obtained using density functional theory. The structure was immersed in a polarizable dielectric continuum with the properties of liquid acetonitrile. Several surfaces (on the right) and midplane cuts (on the left) are shown. The SOMO has a diffuse halo that envelops the whole cluster within this halo, there is a more compact kernel that has nodes at the cavity center and on the molecules.

We will of course be rather more focused here. We shall be concerned with the generic computational strategies needed to address the problems of phase behavior. The physical context we shall explore will not extend beyond the structural organization of the elementary phases (liquid, vapor, crystalline) of matter, although the strategies are much more widely applicable than this. We shall have nothing to say about a wide spectrum of techniques (density functional theory [1], integral equation theories [2], anharmonic perturbation... 

Another approach to liquid glass transition is the self-consistent phonon theory or density functional theory applied to aperiodic structures [112-114]. These theories predict the Lindemann stability criterion for the emergence of a density wave of a given symmetry. Although the finite Lindemann ratio implies a first-order phase transition, the absence of latent heat in glassy systems suggests the presence of an exponentially large number of aperiodic structures that are frozen in at Tg [94,95,110,111],... 

Over the last two decades the exploration of microscopic processes at interfaces has advanced at a rapid pace. With the active use of computer simulations and density functional theory the theory of liquid/vapor, liquid/liquid and vacuum/crystal interfaces has progressed from a simple phenomenological treatment to sophisticated ah initio calculations of their electronic, structural and dynamic properties [1], However, for the case of liquid/crystal interfaces progress has been achieved only in understanding the simplest density profiles, while the mechanism of formation of solid/liquid interfaces, emergence of interfacial excess stress and the anisotropy of interfacial free energy are not yet completely established [2],... 

Density-Functional Theories of Two-Dimensional Melting Simulation Studies of Liquid Structure and Melting in Two Dimensions A. Introduction... 

Roewer G, Herzog U, Trommer K, Muller E, Friihauf S (2002) Silicon Carbide - A Survey of Synthetic Approaches, Properties and Applications 101 59-136 Rosa A, Ricciardi G, Gritsenko O, Baerends EJ (2004) Excitation Energies of Metal Complexes with Time-dependent Density Functional Theory 112 49-116 Rosokha SV, Kochi JK (2007) X-ray Structures and Electronic Spectra of the it-Halogen Complexes between Halogen Donors and Acceptors with it-Receptors. 126 137-160 Rowan SJ, Mather PT (2008) Supramolecular Interactions in the Formation of Thermotropic Liquid Crystalline Polymers. 128 119-149... 

Orientational structure at a liquid vapor-interface of diatomic interaction site fluids has been studied extensively by Gubbins and Thompson using both thermodynamic perturbation theory and molecular dynamics simulation, and by Tarazona and Navascues using perturbation theory. Chacon et al. have applied density-functional theories to these systems. The theoretical methodology and results are reviewed in a comprehensive article by Gubbins, to which the reader is directed for more complete details. 

Although most of the studies of this model have focused on the fluid phase in connection with the theory of electrolyte solutions, its solid-fluid phase behavior has been the subject of two recent computer simulation studies in addition to theoretical studies. Smit et al. [272] and Vega et al. [142] have made MC simulation studies to determine the solid-fluid and solid-solid equilibria in this model. Two solid phases are encountered. At low temperature the substitutionally ordered CsCl structure is stable due to the influence of the coulombic interactions under these conditions. At high temperatures where packing of equal-sized hard spheres determines the stability a substitutionally disordered fee structure is stable. There is a triple point where the fluid and two solid phases coexist in addition to a vapor-liquid-solid triple point. This behavior can be qualitatively described by using the cell theory for the solid phase and perturbation theory for the fluid phase [142]. Predictions from density functional theory [273] are less accurate for this system. 

One recent example of such studies is that of Senda et al.91 who studied liquid Li-Na alloys. They considered a cell containing 61 Li atoms and 39 Na atoms, thus modelling a Lio.6iNao.39 alloy. Subsequently, they applied a molecular dynamics method based on the density-functional theory in calculating the structure of the system for different temperatures. 

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