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171.
Experimental geometries of the HCO· and H2CO·+ -electron radicals were compared with those obtained from calculations with the total energy optimization carried out in the framework of widely used ab initio and semiempirical computational procedures. For each structural form of the radicals, the magnetic resonance parameters calculated in the MNDO approximation were correlated with experimental values determined by ESR spectroscopy. Comparative analysis of the results obtained indicates the possibility of systematic correction of the optimized geometric parameters of free radicals using the results of ESR measurements. A simple computational procedure for automatic geometry correction in the MNDO approximation is developed and evaluated. 相似文献
172.
173.
We consider quadratic diophantine equations of the shape
for a polynomial Q(X1, ..., Xs) Z[X1, ..., Xs] of degree 2.Let H be an upper bound for the absolute values of the coefficientsof Q, and assume that the homogeneous quadratic part of Q isnon-singular. We prove, for all s 3, the existence of a polynomialbound s(H) with the following property: if equation (1) hasa solution x Zs at all, then it has one satisfying
For s = 3 and s = 4 no polynomial bounds s(H) were previouslyknown, and for s 5 we have been able to improve existing boundsquite significantly. 2000 Mathematics Subject Classification11D09, 11E20, 11H06, 11P55. 相似文献
174.
Leo T. Butler 《Geometriae Dedicata》2003,100(1):173-185
Let T
n
denote the group of real n × n upper-triangular matrices with 1s on the diagonal. This paper constructs left-invariant Riemannian and sub-Riemannian metrics on T
3 T
4 whose geodesic flow has a subsystem that factors onto a suspended horseshoe. As a corollary, left-invariant Riemannian metrics with positive topological entropy are constructed on all quotients DT
n
where D is a discrete subgroup of T
n
and n 7. 相似文献
175.
176.
Rafael Herná ndez Marí a J. Vá zquez-Gallo 《Transactions of the American Mathematical Society》2001,353(1):95-115
We determine the degree of some strata of singular cubic surfaces in the projective space . These strata are subvarieties of the parametrizing all cubic surfaces in . It is known what their dimension is and that they are irreducible. In 1986, D. F. Coray and I. Vainsencher computed the degree of the 4 strata consisting on cubic surfaces with a double line. To work out the case of isolated singularities we relate the problem with (stationary) multiple-point theory.
177.
We compute the subdirectly irreducible factors of the free Hermitean (semi)lattice generated by a single element a subject to the relation aa
; we also compute the factors of its induced distributive presentation. 相似文献
178.
Eva Tourís 《Journal of Mathematical Analysis and Applications》2011,380(2):865-881
In this paper we obtain the equivalence of the Gromov hyperbolicity between an extensive class of complete Riemannian surfaces with pinched negative curvature and certain kind of simple graphs, whose edges have length 1, constructed following an easy triangular design of geodesics in the surface. 相似文献
179.
N. A. Tyurin 《Mathematical Notes》1999,65(3):351-357
Three remarks concerning the constructive properties of smooth 4-manifolds with nontrivial Seiberg-Witten invariants are presented.
Translated fromMatematicheskie Zametki, Vol. 65, No. 3, pp. 420–428, March, 1999. 相似文献
180.
Matthew H. Baker 《Proceedings of the American Mathematical Society》1999,127(10):2851-2856
This paper gives a new proof of Kamienny's Criterion using the method of Coleman and Chabauty.