Theoretical Methods

Abstract

Many of the properties of the solid state and chemical systems can be determined solving the Schrödinger equation for a given system. However, states of most of electrons and nuclei have to be accounted for. The solution to many electrons can be obtained by the Hartree Fock (HF) method, using the wavefunction of the electrons, or density functional theory (DFT) based methods, using the density function of the electrons instead of solving the Schrödinger equation. The former method is a base for other approaches used in the quantum chemistry community, whereas the latter method has been largely used in the physics community to study the electronic structure of solids. However, over the last 20 years due to the increased efficiency of computers and the accuracy of the DFT functionals, the number of systems studied using DFT method has increased. As a result of this expansion, systems typically studied using quantum chemistry methods, such as organic and inorganic molecules, are being increasingly often studied with DFT methods because of much better efficiency and high quality which is close to that of the quantum chemistry (QC) methods. Another way to address many body problem is the classical molecular dynamics that is used to derive physical properties of the system from empirical potentials.