-------------------------------------------------------------------- COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER AND THE SCHOOL OF PHYSICS, ASTRONOMY, & COMPUTATIONAL SCIENCES (CSI 898-Sec 001) -------------------------------------------------------------------- Applications of Density-Functional and Tight-Binding Theory in Complex Materials D.A. Papaconstantopoulos Computational Materials Science Center SPACS, George Mason University, Fairfax, VA We present results of density functional theory calculations and tight-binding parametrizations for the complex materials FeSe, Boron and KBH4. We have used the linearized augmented plane wave method (LAPW) in both the generalized gradient approximation and the local density approximation functionals. For the FeSe superconductor, we have performed a full optimization with respect to volume, c/a ratio and internal parameter z, both in paramagnetic and spin-polarized phases. The results indicate a slightly lower total energy for the ferromagnetic case and equilibrium parameters close to experiment. We have also fitted our LAPW results in a tight-binding (TB) basis and obtained a volume-dependent TB Hamiltonian robust enough to use for applications such as molecular dynamics, vacancy formation energies, and even for exploring properties beyond the DFT capabilities. We also present a TB study of predicting the complex allotrope structures of the element Boron. Boron crystal structures have many atoms in the unit cell making them computationally demanding if LAPW is used. Therefore the NRL-TB approach is suitable and facilitates the prediction of complex crystal structures. Additionally, a study of the formation energy of charged hydrogen vacancies in the compound KBH4 will be presented. October 21, 2013 4:30 pm Room 3301, Exploratory Hall, Fairfax Campus Refreshments will be served at 4:15 PM. ---------------------------------------------------------------------- Find the schedule at http://www.cmasc.gmu.edu/seminars.htm