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991.
Ramachandran maps of neutral and ionized HCO–Gly–NH2 and HCO–Ala–NH2 peptide models have been built at the B3LYP/6‐31++G(d,p) level of calculation. Direct optimizations using B3LYP and the recently developed MPWB1K functional have also been carried out, as well as single‐point calculations at the CCSD(T) level of theory with the 6‐311++G(2df,2p) basis set. Results indicate that for both peptide models ionization can cause drastic changes in the shape of the PES in such a way that highly disallowed regions in neutral PES become low‐energy regions in the radical cation surface. The structures localized in such regions, and are highly stabilized due to the formation of 2‐centre‐3‐electron interactions between the two carbonyl oxygens. Inclusion of solvent effects by the conductor‐like polarizable continuum model (CPCM) shows that the solute‐solvent interaction energy plays an important role in determining the stability order. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009 相似文献
992.
Marek Niezgoda 《Journal of Mathematical Analysis and Applications》2009,354(1):111-9789
In this paper we study translation-invariant maps on a linear space. A method for estimating quantities induced by such maps is presented. Applications for differences of operators, commutators, G-contractive maps and Grüss type inequalities are also given. 相似文献
993.
María Burgos Moisés Villegas-Vallecillos 《Journal of Mathematical Analysis and Applications》2009,359(1):1-117
Let T:Lip0(X)→Lip0(Y) be a surjective map between pointed Lipschitz ∗-algebras, where X and Y are compact metric spaces. On the one hand, we prove that if T satisfies the non-symmetric norm ∗-multiplicativity condition:
994.
We prove that a diffeomorphism of a manifold with an Ehresmann connection is an automorphism of the Ehresmann connection,
if and only if, it is a totally geodesic map (i.e., sends the geodesies, considered as parametrized curves, to geodesies)
and preserves the strong torsion of the Ehresmann connection. This result generalizes and to some extent strengthens the classical
theorem on the automorphisms of a D-manifold (manifold with covariant derivative).
The second author is supported by the Hungarian Nat. Sci. Found. (OTKA), Grant No. NK68040. 相似文献
995.
A. Amini-Harandi A.P. Farajzadeh 《Nonlinear Analysis: Theory, Methods & Applications》2009,71(11):5151-5156
Suppose X is a compact admissible subset of a hyperconvex metric spaces M, and suppose F:XM is a quasi-lower semicontinuous set-valued map whose values are nonempty admissible. Suppose also G:XX is a continuous, onto quasi-convex set-valued map with compact, admissible values. Then there exists an x0X such that As applications, we give some coincidence and fixed point results for weakly inward set-valued maps. Our results, generalize some well-known results in literature. 相似文献
996.
We introduce a new composite iterative scheme to approximate a zero of an m-accretive operator A defined on uniform smooth Banach spaces and a reflexive Banach space having a weakly continuous duality map. It is shown that the iterative process in each case converges strongly to a zero of A. The results presented in this paper substantially improve and extend the results due to Ceng et al. [L.C. Ceng, H.K. Xu, J.C. Yao, Strong convergence of a hybrid viscosity approximation method with perturbed mappings for nonexpansive and accretive operators, Taiwanese J. Math. (in press)], Kim and Xu [T.H. Kim, H.K. Xu, Strong convergence of modified Mann iterations, Nonlinear Anal. 61 (2005) 51–60] and Xu [H.K. Xu, Strong convergence of an iterative method for nonexpansive and accretive operators, J. Math. Anal. Appl. 314 (2006) 631–643]. Our work provides a new approach for the construction of a zero of m-accretive operators. 相似文献
997.
We investigate localization phenomena and stability properties of quasiperiodic oscillations in N degree of freedom Hamiltonian systems and N coupled symplectic maps. In particular, we study an example of a parametrically driven Hamiltonian lattice with only quartic coupling terms and a system of N coupled standard maps. We explore their dynamics using the Generalized Alignment Index (GALI), which constitutes a recently developed numerical method for detecting chaotic orbits in many dimensions, estimating the dimensionality of quasiperiodic tori and predicting slow diffusion in a way that is faster and more reliable than many other approaches known to date. 相似文献
998.
Gregg Musiker 《Journal of Algebraic Combinatorics》2009,30(2):255-276
Let q be a power of a prime, and E be an elliptic curve defined over
. Such curves have a classical group structure, and one can form an infinite tower of groups by considering E over field extensions
for all k≥1. The critical group of a graph may be defined as the cokernel of L(G), the Laplacian matrix of G. In this paper, we compare elliptic curve groups with the critical groups of a certain family of graphs. This collection
of critical groups also decomposes into towers of subgroups, and we highlight additional comparisons by using the Frobenius
map of E over
.
This work was partially supported by the NSF, grant DMS-0500557 during the author’s graduate school at the University of California,
San Diego, and partially supported by an NSF Postdoctoral Fellowship. 相似文献
999.
1000.
A moving frame formulation of non-stretching geometric curve flows in Euclidean space is used to derive a 1+1 dimensional hierarchy of integrable SO(3)-invariant vector models containing the Heisenberg ferromagnetic spin model as well as a model given by a spin vector version of the mKdV equation. These models describe a geometric realization of the NLS hierarchy of soliton equations whose bi-Hamiltonian structure is shown to be encoded in the Frenet equations of the moving frame. This derivation yields an explicit bi-Hamiltonian structure, recursion operator, and constants of motion for each model in the hierarchy. A generalization of these results to geometric surface flows is presented, where the surfaces are non-stretching in one direction while stretching in all transverse directions. Through the Frenet equations of a moving frame, such surface flows are shown to encode a hierarchy of 2+1 dimensional integrable SO(3)-invariant vector models, along with their bi-Hamiltonian structure, recursion operator, and constants of motion, describing a geometric realization of 2+1 dimensional bi-Hamiltonian NLS and mKdV soliton equations. Based on the well-known equivalence between the Heisenberg model and the Schrödinger map equation in 1+1 dimensions, a geometrical formulation of these hierarchies of 1+1 and 2+1 vector models is given in terms of dynamical maps into the 2-sphere. In particular, this formulation yields a new integrable generalization of the Schrödinger map equation in 2+1 dimensions as well as a mKdV analog of this map equation corresponding to the mKdV spin model in 1+1 and 2+1 dimensions. 相似文献