# Dresden 2014 – wissenschaftliches Programm

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# HL: Fachverband Halbleiterphysik

## HL 77: Frontiers of electronic structure theory - Non-equilibrium phenomena at the nano-scale V (organized by O)

### HL 77.7: Vortrag

### Mittwoch, 2. April 2014, 18:00–18:15, TRE Ma

**Strong Parallelization of Real-Space DFT Calculations** — •Andrea Nobile^{1,2}, Paul Baumeister^{1,2}, Daniel Wortmann^{1}, and Stefan Blügel^{1} — ^{1}Peter Grünberg Institut & Institute for Advanced Simulation, Forschungzentrum Jülich and JARA, 52425 Jülich, Germany — ^{2}Jülich Supercomputing Center, Forschungzentrum Jülich, 52425 Jülich, Germany

The rapid change in modern supercomputing architectures poses a challenge to well established DFT codes. In particular, the increase in raw floating point power obtained through parallelism at different levels is not easily exploitable by using the traditional direct diagonalization methods. We will present our new real-space Projector Augmented Wave (PAW) implementation. The real-space representation of the wave functions, densities and potentials, enables the usage of very flexible boundary conditions and naturally adapts to massively parallel architectures. Parallelism can be exploited in the form of domain decomposition of the three dimensional grid, k-point sampling and bands. The kinetic energy operator, realized as a finite difference stencil, is localized. As a consequence the real-space representation of the Hamiltonian is sparse. This limits the amount of necessary communications and allows an application of the operator to a trial vector in order(N) operations. We will present results about the efficiency of the most numerical intensive parts of the code and we will compare the accuracy of the calculations for reference systems with other established DFT methods.