Density functional approaches interactions

With the addition of a pseudopotential interaction between electrons and metal ions, the density-functional approach has been used82 to calculate the effect of the solvent of the electrolyte phase on the potential difference across the surface of a liquid metal. The solvent is modeled as a repulsive barrier or as a region of dielectric constant greater than unity or both. Assuming no specific adsorption, the metal is supposed to be in contact with a monolayer of water, modeled as a region of 3-A thickness (diameter of a water molecule) in which the dielectric constant is 6 (high-frequency value, appropriate for nonorientable dipoles). Beyond this monolayer, the dielectric constant is assumed to take on the bulk liquid value of 78, although the calculations showed that the dielectric constant outside of the monolayer had only a small effect on the electronic profile. 

A large class of time-dependent quantum problems involves strongly interacting coupled fields requiring self-consistent non-perturbative and non-adiabatic approaches. We present here a general framev ork for analyzing these, based on Liouvillean Quantum Field Dynamics. Thus a multifunctional extension of the time-dependent density functional approach to many-body problems is... 

Fronzoni G, Decleva P (1998) Ab-initio Cl calculations of the C Is and Cl Is and 2p core excitation spectra of the freon molecules CC14, CFC13, CF2C12, and CF3C1. Chem Phys 237 21-42 Fronzoni G, Stener M, Decleva P, De Alti G (1998) Theoretical study of the Cl Is and 2p near edge photoabsorption spectra of HC1 by accurate ab-initio configuration interaction and density functional approaches. Chem Phys 232 9-23... 

Burns, L. A., Vazquez-Mayagoitia, A, Sumpter, B. G., and Sherrill, C. D. (2011). Density-functional approaches to noncovalent interactions A comparison of dispersion corrections (DFT-D), exchange-hole dipole moment (XDM) theory, and specialized functionals,/ Chem. Phys. 134, p. 084107, doi 10.1063/1.3545971. 

In recent years, much progress has been made in understanding the thermal properties of simple liquids and colloidal systems [54]. Studies of these systems are often based on the density functional approach, in which the free energy is written as a sum of two contributions, one describing the hard-core repulsion and thus the steric hindrance of the particles, and a second, the long-range and possibly orientation-dependent interactions between them. 

General expressions for the flexocoefiicients of nematic liquid crystals have been obtained in terms of the direct correlation function using the powerful density functional approach. These expressions have been used to obtain some interesting numerical results using the Perkus-Yevic approximation for the pair correlation function. The results from the density functional theory have also been used in computer simulations of flexoelectricity using model bent-core molecules interacting via the Gay-Berne potential. Alternative general expressions for the flexocoefiicients have... 

The EXX approach has several advantages over the standard density-functional approaches we have studied so far The self-interaction, discussed in the previous section, is absent and the problems related to the asymptotic 1/r behaviour of the exchange potential, i.e. the subject of Section 9, are removed. As we shall see below, this leads first of all to a significantly improved agreement between ionization potentials and the orbital energies. 

The density-functional based calculations described above were done for small apphed potential bias between the electrodes. In contrast, the density functional approach of Hirose and Tsukada [172] calculates the electronic structure of a metal-insulator-metal system under strong apphed bias. The main difference from the density functional approaches described above comes in the way the effective one-electron potential is calculated. The potential used in this work contains the usual contributions from the Coulomb and the exchange[Pg.611]

The aim of this article was to review some of the recent progress in calculating the electronic and structural properties of condensed matter using the ab initio pseudopotential density functional approach. Specific examples have been given for a variety of properties and systems. These include the static structural properties, the vibrational properties, phonon—phonon interactions, solid-solid structural phase transitions, surface... 

---