Theoretical investigation of nitrogen-vacancy defects in silicon

Nitrogen-vacancy defects are important for the material properties of silicon and for the performance of silicon-based devices. Here, we employ spin polarized density functional theory to calculate the minimum energy structures of the vacancy-nitrogen substitutional, vacancy-dinitrogen substitutionals, and divacancy-dinitrogen substitutionals. The present simulation technique enabled us to gain insight into the defect structures and charge distribution around the doped N atom and the nearest neighboring Si atoms. Using the dipole–dipole interaction method, we predict the local vibration mode frequencies of the defects and discuss the results with the available experimental data

Application of the magnetic-electric two-dimensional Euclidean group to the case of anyons

The magnetic-electric two-dimensional Euclidean symmetry MEE(2) is applied to the case of anyons. It is shown that in this formalism both Bloch’s theorem and acceleration theorem for charged anyons in periodic fields are straightforward The relation between these two theorems and the anyonic superconductivity is discussed and certain suggestions are put forward. (C) 1998 Elsevier Science B.V

Origin of infrared bands in neutron-irradiated silicon

Infrared absorption measurements were made of the localized vibrational modes due to defects produced in Czochralski-grown Si material after irradiation with fast neutrons and subsequent thermal treatments. The investigation was focused, in particular, on three satellite bands in the region of the A center, located at 839, 833 and 824 cm(-1) respectively, the annealing behavior of which was carefully monitored. Correlation of our results with previous infrared, electron paramagnetic resonance and positron annihilation studies favors attributing these bands to the V2O, V3O2 and V2O2 defects respectively. In addition, semiempirical calculations were carried out for the vibrational frequencies of these defects, and the predicted values are in agreement with the above assignments. (C) 1997 American Institute of Physics

Natural entropy fluctuations discriminate similar-looking electric signals emitted from systems of different dynamics

Complexity measures are introduced that quantify the change of the natural entropy fluctuations at different length scales in time series emitted from systems operating far from equilibrium. They identify impending sudden cardiac death (SD) by analyzing 15 min electrocardiograms, and comparing to those of truly healthy humans (H). These measures seem to be complementary to the ones suggested recently [Phys. Rev. E 70, 011106 (2004)] and altogether enable the classification of individuals into three categories: H, heart disease patients, and SD. All the SD individuals, who exhibit critical dynamics, result in a common behavior