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41.
A biased potential molecular dynamics simulation approach, accelerated molecular dynamics (AMD), has been implemented in the framework of ab initio molecular dynamics for the study of chemical reactions. Using two examples, the double proton transfer reaction in formic acid dimer and the hypothetical adiabatic ring opening and subsequent rearrangement reactions in methylenecyclopropane, it is demonstrated that ab initio AMD can be readily employed to efficiently explore the reactive potential energy surface, allowing the prediction of chemical reactions and the identification of metastable states. An adaptive variant of the AMD method is developed, which additionally affords an accurate representation of both the free-energy surface and the mechanism associated with the chemical reaction of interest and can also provide an estimate of the reaction rate. 相似文献
42.
Frantz MC Pierce JG Pierce JM Kangying L Qingwei W Johnson M Wipf P 《Organic letters》2011,13(9):2318-2321
JP4-039 is a novel nitroxide conjugate capable of crossing lipid bilayer membranes and scavenging reactive oxygen species (ROS). An efficient and scalable one-pot hydrozirconation-transmetalation-imine addition methodology has been developed for its asymmetric preparation. Furthermore, this versatile methodology allows for the synthesis of cyclopropyl and fluorinated analogs of the parent lead structure. 相似文献
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Wm. Lerch R. H. Bogue E. S. Shepherd G. A. Rankin F. E. Wright F. Ferrari J. Stanton Pierce W. C. Setzer F. Strumpf und R. H. H. Stanger 《Fresenius' Journal of Analytical Chemistry》1930,81(12):476-480
Ohne Zusammenfassung 相似文献
47.
John F. Pierce 《Journal of Elasticity》1959,37(3):243-280
The sets of polynomial stress-strain relations for elastic points which are transversely hemitropic and transversely isotropic are presented as projections of free algebraic modules having 20 and 10 generators, respectively. Complete sets of relations for the projections are presented which allow the sets of interest to be identified as free submodules having 12 and 6 generators, respectively. The results are established using the Cartan decomposition of the representation of the adjoint action of the two-dimensional rotation and orthogonal groups on the space of three-by-three symmetric matrices. The results are compared to known representations for nonlinear transversely isotropic stress-strain relations and for linear, transversely hemitropic and transversely isotropic ones.Work supported in part by National Science Foundation Grant INT-9106519. 相似文献
48.
A set of simultaneously triangularizable square matrices over an arbitrary field is considered. If the matrices are also quasicommutative, then they have a common eigenvector for every distinct set of corresponding eigenvalues. Conversely, if the set of matrices has this common eigenvector property hereditarily (i.e., for every set of corresponding blocks in every simultaneous block triangularization), then the matrices are quasicommutative. 相似文献
49.
A. Jameson L. Martinelli N.A. Pierce 《Theoretical and Computational Fluid Dynamics》1998,10(1-4):213-237
This paper describes the formulation of optimization techniques based on control theory for aerodynamic shape design in viscous
compressible flow, modeled by the Navier–Stokes equations. It extends previous work on optimization for inviscid flow. The
theory is applied to a system defined by the partial differential equations of the flow, with the boundary shape acting as
the control. The Fréchet derivative of the cost function is determined via the solution of an adjoint partial differential
equation, and the boundary shape is then modified in a direction of descent. This process is repeated until an optimum solution
is approached. Each design cycle requires the numerical solution of both the flow and the adjoint equations, leading to a
computational cost roughly equal to the cost of two flow solutions. The cost is kept low by using multigrid techniques, in
conjunction with preconditioning to accelerate the convergence of the solutions. The power of the method is illustrated by
designs of wings and wing–body combinations for long range transport aircraft. Satisfactory designs are usually obtained with
20–40 design cycles.
Received 5 February 1997 and accepted 30 May 1997 相似文献
50.
Summary The purpose of this article is to obtainL
2 and uniform norm error estimates for the Galerkin approximation of the solution of certain boundary value problems via a comparison with then-norm projection of the solution. In some cases, these estimates constitute an improvement over known results.This research was supported in part by AEC Grant (11-1)-2075. 相似文献