A graph theoretic approach to the representation of N particle systems involving arbitrary single-particle spin is presented. The method is a generalization of the Distinct Row Table (DRT ) technique employed by Shavitt in developing the graphical unitary group approach (GUGA ) to electronic spin-orbitals. A detailed analysis of the DRT and GUGA representations is presented based on several theoretical considerations and computer-tested implementations. The use of the representation to establish rules concerning the evaluation of the matrix elements of the group generators is also discussed. 相似文献
Double-Octahedra Clusters [V2O9] in the Crystal Structure of Vanadium (III) Diphosphate, V4(P2O7)3 . As the first example for MIII diphosphates the crystal structure of V4(P2O7)3 (“ I ”) has been determined by means of X-ray diffraction of single crystals. I – according to [7] obtainable by thermal interaction of V2O5, H3PO3, and H3PO4 – crystallizes orthorhombically (data see above); in the unit cell two kinds of isolated doubleoctahedra (clusters) [V2O9], having the symmetry Cs, exist. Due to a mutual face-connection of the octahedra, within these clusters relatively short V–V distances are resulting: 2.774(8) and 3.026(7) Å. The diphosphate anions, O3POPO34? (three kinds; each having the symmetry Cs and staggered conformation), exhibit POP bond angles of 170°, being remarkably large for non-centrosymmetry. Because of the [M2IIIO9] clusters in I , and also in the isostructural diphosphates Cr4(P2O7)3 and Fe4(P2O73), magnetic investigations seem to be challenged. 相似文献
It's not easy being green : Real‐time visualization of labeled ribosomes and de novo synthesized green fluorescent protein molecules using single‐molecule‐sensitive fluorescence microscopy demonstrates that the mutant GFPem is produced with a characteristic time of five minutes. Fluorescence of the fastest GFP molecules appears within one minute (see picture).
Using a generalized theory of manifolds, based on the ideas and techniques of nonstandard analysis, a link is established
between sequences of computable structures converging to a classical manifold and certain manifold-like structures involving
anticommuting variables. The supermanifolds appearing here may be interpreted as a kind of representation of sequences of
computable structures. 相似文献