Bridging the length and time scales: from ab initio electronic structure calculations to macroscopic proportions

Density functional theory (DFT) primarily provides a good description of the electronic structure. Thus, DFT primarily deals with length scales as those of a chemical bond, i.e. 10^-10 meter, and with time scales of the order of atomic vibrations, i.e. 10^-13 seconds. However, several interesting phenomena happen and/or become observable on different scales, namely meso- or macroscopic lengths and on time scales of seconds or even minutes. To bridge the gap between 10^-13 seconds and a second or between 10^-10 meter and 10 and more nano meters is one of the important challenges we are facing today. In this paper we show how we are overcoming these time and size problems for the example of crystal growth and the evolution of nano-scale structures. The key is a kinetic Monte Carlo approach with detailed input from DFT calculations of the relevant atomistic processes.Comment: 13 pages, 5 figures, to be published in Comments on Condens. Matt. Phys. (1998). Other related publications can be found at http://www.rz-berlin.mpg.de/th/paper.htm

Regional Dynamics of Innovation - Investigating the Co-Evolution of Patents, R&D, and Employment

We investigate the lead-lag relationship between growth of patent applications, growth of R&D, and growth of total sectoral employment for 270 German labour market regions over the period 1999-2005. Our unique panel dataset includes information on four two-digit industries, namely Chemistry, Transport equipment, Medical & Optical Equipment as well as Electrics & Electronics. The results obtained from a vector autoregression model show that an increased innovative activity is associated with subsequent growth of employment in the Medical & Optical Equipment industry as well as in the Electrics & Electronics sector. With respect to the latter growth of patent applications is also associated with subsequent growth of R&D employees indicating either a 'success-breeds-success' story or benefits due to agglomeration economies at the level of the region. However we do not find those effects for the other industries due to their idiosyncratic innovation and patenting behaviour.innovation, regional dynamics, r&d growth, employment growth, patent growth

Magnetization of Planar Four-Fermion Systems

We consider a planar system of fermions, at finite temperature and density, under a static magnetic field parallel to the two-dimensional plane. This magnetic field generates a Zeeman effect and, then, a spin polarization of the system. The critical properties are studied from the Landau's free energy. The possible observable consequences of the magnetization of planar systems such as polymer films and graphene are discussed.Comment: 10 pages, two-column, revtex style, 6 eps figures. Published versio