Atlas of German Dialects in the Czech Republic

Research project P 14099 Atlas of German Dialects in the Czech Republic Hermann SCHEURINGER 24.01.2000 The project "Atlas of the historical German dialects in the Czech Republic (ADT)" constitutes an international joint project of scientists and -universities in the Czech Republic, in Germany, and in Austria. The immediate aims of the project are: * Research in and documentation of the German dialects in Bohemia and Moravia-Silesia by means of a direct enquete with members of the German language minority, i e. non-post-World-War-H-exiled speakers of German - as long as this is still possible * Concentrated research in Czech influence in and interference, with the German dialects, and - by this way - linguistic documentation of almost a millenium of mainly peaceful co-existence of Germans and Czechs As an indirect aim of the project we see the improvement of scientific and - generally human relations between speakers of German and of Czech in the centre of Europe. We believe that unprejudiced research in the German part of the (linguistic) history of the Bohemian lands constitutes an important contribution to the process of tearing down walls of hostility and prejudice, connecting a common past with a common future.

Carbon nanotubes are novel carbon based materials, which are formed by rolling up a honeycomb graphite sheet. The outer wall of these nanotubes can be as thin as a single carbon atom, and the diameters of the tubes approach a few nanometers. It is believed that such ultra thin nanotubes might be used either as electronic wires or as electronic switches in next generation computers. Developing a deeper theoretical understanding for such tubes was the main aim of the present research project. Due to their reduced dimensionality nanotubes posses intriguing new properties which are related to the quantum nature of the electronic states traveling in the circumferential direction, e.g. after the circumference, the phase of an electron must match with the original phase. Another quantum mechanism that has been known to exist in one dimensional wires is called Peierls instability: at low temperatures ultra thin wires are in principle unstable and should distort or twist in such a manner that they become non metallic. Despite this theoretical prediction, such an instability has not been observed experimentally for nanotubes. The present calculations shed light on this peculiarity and indicate that for carbon nanotubes such instabilities indeed exist, but are so weak that a permanent distortion does not occur. Instead, metallic carbon nanowires posses one specific vibrational mode which is significantly softer than in non metallic wires. When the carbon atoms in the nanotube swing back and forth in a manner compatible to this particular mode, a band-gap opens (they become non-metallic, but only temporarily on a fs timescale). This mode softening has been observed but was not understood before the present theoretical study. Furthermore, the project investigated how the encapsulation of Buckminster fullerenes into nanotubes changes their electronic conductivity. Experimentally profound modifications have been observed under specific conditions, and it was suggested that these modifications can be used to tune carbon wires and transistors. Unfortunately the theoretical calculations tell a different story. The Buckminster fullerenes modify the electronic structure of the tubes, but only slightly and the modifications are far too small to allow a tuning of the relevant transport properties in actual devices.