Endohedral Impurities in Carbon Nanotubes

A generalization of the Anderson model that includes pseudo-Jahn-Teller impurity coupling is proposed to describe distortions of an endohedral impurity in a carbon nanotube. Treating the distortion within mean-field theory, spontaneous axial symmetry breaking is found when the vibronic coupling strength g exceeds a critical value g$_c$. The effective potential in the symmetry-broken state is found to have O(2) symmetry, in agreement with numerical calculations. For metallic zigzag nanotubes endohedrally-doped with transition metals in the dilute limit, the low-energy properties of the system may display two-channel Kondo behavior; however, strong vibronic coupling is seen to exponentially suppress the Kondo energy scale.Comment: 4 pages, 2 figure

Theory of Spontaneous Polarization of Endohedral Fullerenes

A pseudo-Jahn-Teller model describing central atom distortions is proposed for endohedral fullerenes of the form A@C$_{60}$ where A is either a rare gas or a metal atom. A critical (dimensionless) coupling $g_c$ is found, below which the symmetric configuration is stable and above which inversion symmetry is broken. Vibronic parameters are given for selected endohedral fullerenes.Comment: 4 pages, REVTEX, 1 Postscript figure. [Phys. Rev. Lett. (in press)

C 1s Autoionization Study of Electron Hopping Rates in Solid C60

We present C 1s autoionization studies of condensed and Xe matrix-isolated C60 molecules which give direct information on electron hopping rates in solid C60 in the presence of a C 1s vacancy. These rates vary dramatically for the first three C 1s absorption excitation maxima in a pattern consistent with strong electron-electron correlations. Hopping associated with the second excited state involves extramolecular screening comparable to the Mott-Hubbard pseudogap predicted for K3C60, suggesting intramolecular correlations do not dominate electron transport in the alkali fullerides.

Women's perceived work environment after stress-related rehabilitation: experiences from the ReDO project.

The study aimed to investigate (a) if women's perceptions of their work environment changed during a 16-week rehabilitation period and at a 12-month follow-up; (b) whether such changes were related to outcomes in terms of return to work, well-being and valued occupations

Principal axes for structural fatigue

Recent advances in the analysis of joint seakeeping processes are applied to the accumulation of spectral fatigue cycles. The methods of cross co-spectral moments and techniques adopted from the determination of principal angles for seakeeping processes are used to determine orientation of the most severe plane for the accumulation of spectral fatigue cycles and the distribution of stress cycles on that plane. The theory presented considers all aspects of the wave loads experienced over the life of the structure and uses linear theory to predict lifetime fatigue using more efficient techniques than equally comprehensive time-domain simulation. Three methods of determining the orientation of the principal plane and their theoretical differences are discussed. Quantitative comparisons are presented in the time, frequency and probability domains to illustrate differences and demonstrate consistency

C K-edge in polymerized C60_{60} : experiment and theory

The paper has been withdrawnComment: 5 pages, 5 figure