32 research outputs found
Obstructions to Lagrangian concordance
We investigate the question of the existence of a Lagrangian concordance between two Legendrian knots in R3. In particular, we give obstructions to a concordance from an arbitrary knot to the standard Legendrian unknot, in terms of normal rulings. We also place strong restrictions on knots that have concordances both to and from the unknot and construct an infinite family of knots with nonreversible concordances from the unknot. Finally, we use our obstructions to present a complete list of knots with up to 14 crossings that have Legendrian representatives that are Lagrangian slice
Sutured ECH is a natural invariant
We show that sutured embedded contact homology is a natural invariant of sutured contact 3-manifolds which can potentially detect some of the topology of the space of contact structures on a 3-manifold with boundary. The appendix, by C. H. Taubes, proves a compactness result for the completion of a sutured contact 3-manifold in the context of Seiberg-Witten Floer homology, which enables us to complete the proof of naturality
First-Principles Investigation of Bilayer Fluorographene
\textit{Ab initio} calculations within the density functional theory
formalism are performed to investigate the stability and electronic properties
of fluorinated bilayer graphene (bilayer fluorographene). A comparison is made
to previously investigated graphane, bilayer graphane, and fluorographene.
Bilayer fluorographene is found to be a much more stable material than bilayer
graphane. Its electronic band structure is similar to that of monolayer
fluorographene, but its electronic band gap is significantly larger (about 1
eV). We also calculate the effective masses around the -point for
fluorographene and bilayer fluorographene and find that they are isotropic, in
contrast to earlier reports. Furthermore, it is found that bilayer
fluorographene is almost as strong as graphene, as its 2D Young's modulus is
approximately 300 .Comment: 8 pages, 5 figure