Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 82: Poster Focus Session: Frontiers of Electronic-Structure Theory - Correlated Electron Materials

O 82.14: Poster

Mittwoch, 14. März 2018, 18:15–20:30, Poster A

Developing Density Functional Based Tight-Binding Methods within a Self-Consistent Field Density Functional Theory Framework — •Frederick Stein, Jens Kunstmann, and Gotthard Seifert — TU Dresden, Germany

The Density-Functional Tight-Binding (DFTB) method is an approximate density functional theory scheme that is routinely used in computer simulations with large system sizes or long simulation times. The method traditionally exists in a non-selfconsistent (DFTB0) and a charge-selfconsistent (SCC-DFTB) flavor. Here we develop a self-consistent field DFTB (SCF-DFTB) scheme that is very general and directly allows improvements of traditional DFTB methods. We demonstrate how the SCC-DFTB formalism can be derived from SCF-DFTB without the use of a second-order expansion of the total energy. This leads to a new interpretation of SCC-DFTB and the involved Hubbard parameter in terms of a flexible basis set. Furthermore we use small molecules to study SCF-DFTB variants with spherical and non-spherical corrections of the DFTB0 Hamiltonian. Our results indicate that the success of DFTB is based on multiple, well-balanced approximations. Attempts to only correct individual approximations are not leading to better results.