Search results for "Projective representation"
showing 4 items of 4 documents
A combinatorial algorithm related to the geometry of the moduli space of pointed curves
2002
As pointed out in Arbarello and Cornalba ( J. Alg. Geom. 5 (1996), 705–749), a theorem due to Di Francesco, Itzykson, and Zuber (see Di Francesco, Itzykson, and Zuber, Commun. Math. Phys. 151 (1993), 193–219) should yield new relations among cohomology classes of the moduli space of pointed curves. The coefficients appearing in these new relations can be determined by the algorithm we introduce in this paper.
Spectroscopie des hexafluorures à nombre impair d'électrons
1995
From a theoretical point of view, a tensorial formalism adapted to the study of molecules or octahedral ions with a half-integer angular momentum has been developed for the first time. We have used here the method of projective representations, more consistent than that of double groups. A complete set of coupling coefficients and formulas, as well as the corresponding computing programs have been elaborated. This has firstly allowed to write a simple model describing the vibronic structure of colored hexafluorides. Then, somme applications of this formalism to the study of rovibronic couplings of XY6 molecules in a fourfold degenerate electronic state have been considered, especially conce…
On a projective representation of chain geometries
1984
We define a distance d on the set of r-spaces of an n-space. By the transfer of d to the GrasmannianG=G(n, r) we obtain a distinguished class of normal rational curves of order 1, the “1-distance lines’, 1=1,..., r, which are in 1–1-correspondence to the so-called “generalized reguli of type (r, 1)”.
Deformation modes according to irreducible representations
2001
Abstract A method for obtaining distortion fields in a crystal from a given irreducible representation of the underlying space group is described in Ref.[1]. The method is based on projection operators of the group theory, it is graphically oriented and thus calculation free. As an example (Space group P421m)complete sets of representation matrices ara analytically calculated for all irreducible representations which correspond to all wave vectors of the form k= (q, q, 0). Linear independent atomic displacement modes in the (3×3×1) supercell, which are induced by the two irreducible representations with k = (1/3,1/3,0) are explicitly determined: the obtained atomic displacement fields are p…