Advancement of the DFTB-method

The simulation of different processes in solids and biological systems gained more and more importance over the last decade. Efficient algorithms and powerful processors enable users to observe systems of hundreds of thousands of atoms for several microseconds. The challenge for researchers is to find a reasonable compromise between computational cost and the readily available information of a simulation. So-called ab-initio methods or the Density Functional Theory (DFT) allow the investigation of most system properties. But since they have solve Schrödinger's equation by the calculation of complex integrals, they are only available on a small scale. On the other hand there are very efficient molecular mechanics or force field methods. But since these are of empirical nature they cannot describe all properties of a system with sufficient accuracy.
Density Functional Tight Binding (DFTB) describes a class of approximative DFT methods [1, 2, 3]. Those are faster than ab-initio or DFT by up to three orders of magnitude through pre-calculated integrals (so they do not have to be computed on runtime). DFTB is known for its similarity to DFT theory which shows in the stability of simulations, especially in large biological systems [4]. Another benefit is that it is possible to calculate both molecular systems and solids with the same theory.
Future developments aim to correct shortcomings of DFTB in biochemical systems. A better understanding of structural and energetic information of supramolecular systems and non-binding interactions are the main goals of our research. The latter takes place in several cooperations with Asia, Amerika and, of course, Europe. Through these efforts we aim to promote the applicability of efficient quantum chemical methods in biological research and development.

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[1] D. Porezag, T. Frauenheim, T. Köhler, G. Seifert, and R. Kaschner Phys. Rev. B 51 (1995) 12947.
[2] M. Elstner, D. Porezag, G. Jungnickel, J. Elsner, M. Haugk, T. Frauenheim, S. Suhai, and G. Seifert Phys. Rev. B 58 (1998) 7260.
[3] M. Gaus, Q. Cui, and M. Elstner J. Chem. Theory Comput. 7 no. 4, (2011) 931.
[4] H. Liu, M. Elstner, E. Kaxiras, T. Frauenheim, J. Hermans, and W. Yang PROTEINS 44 (2001) 484.