Ad
related to: introduction to density functional theory pdf file
Search results
Results From The WOW.Com Content Network
Density functional theory (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (or nuclear structure) (principally the ground state) of many-body systems, in particular atoms, molecules, and the condensed phases.
The Density Functional Based Tight Binding method is an approximation to density functional theory, which reduces the Kohn-Sham equations to a form of tight binding related to the Harris functional. The original [ 1 ] approximation limits interactions to a non-self-consistent two center hamiltonian between confined atomic states.
In practice, the density functional is known exactly except for two terms. These are the electronic kinetic energy and the exchange – correlation energy. The lack of the true exchange–correlation functional is a well known problem in DFT, and there exists a huge variety of approaches to approximate this crucial component.
The kinetic energy expression of Thomas–Fermi theory is also used as a component in more sophisticated density approximation to the kinetic energy within modern orbital-free density functional theory. Working independently, Thomas and Fermi used this statistical model in 1927 to approximate the distribution of electrons in an atom.
The density response function, the functional derivative of the density with respect to the external potential, should be causal: a change in the potential at a given time can not affect the density at earlier times. The response functions from the Dirac action however are symmetric in time so lack the required causal structure.
In physics and quantum chemistry, specifically density functional theory, the Kohn–Sham equation is the non-interacting Schrödinger equation (more clearly, Schrödinger-like equation) of a fictitious system (the "Kohn–Sham system") of non-interacting particles (typically electrons) that generate the same density as any given system of interacting particles.
Giovanni Vignale is an Italian American physicist and Professor of Physics at the University of Missouri.Vignale is known for his work on density functional theory - a theoretical approach to the quantum many-body problem - and for several contributions to many-particle physics and spintronics.
The theory is completed by specifying the chemical potential for a second (possibly bulk) phase. In an equilibrium process, μ I =μ II . Lattice density functional theory has several advantages over more complicated free volume techniques such as Perturbation theory and the statistical associating fluid theory , including mathematical ...