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91.
The procedure ‘Multimode’ was introduced by Carter and Bowman [1998, J. chem. Phys., 108, 43971, to calculate the vibrations of polyatomic molecules using normal coordinates. Recently Carter and Handy have introduced an extension to ‘Multimode’ to include one large amplitude torsional vibration for molecules for which an analytical potential is available. This procedure is now extended to molecules for which ab initio potential data may be calculated. Glyoxal (CHOCHO) is studied using the density functional approach to generate the potential surface data. The full J = 0 vibrational spectra is presented. 相似文献
92.
DAVID J. WALES 《Molecular physics》2013,111(20):3285-3305
A theoretical framework is developed for the calculation of rate constants by sampling connected pathways composed of local minima and transition states that link them together. The theory is applicable to two-state or effective two-state systems and is applied to permutational or morphological isomerization in a two-dimensional cluster of seven Lennard-Jones atoms, water clusters containing eight and nine molecules, and a cluster of 38 Lennard-Jones atoms, which exhibits a double funnel energy landscape. 相似文献
93.
According to both UB3LYP/6-311G* and UMP2/6-311G* calculations, the lowest energy conformer of the S+ 8 radical cation possesses Cs symmetry. However, there are three other structures with low relative energies that do not exceed 6.5 kcal mol?1. These conformers, which are found to be very prone to pseudorotation, are predicted to interconvert readily. The fluxional nature of S+ 8 is expected to facilitate its reactions with organic species where a specific conformation is demanded by steric constraints, which may explain its high reactivity towards PAHs with crowded hydrogen atoms. 相似文献
94.
DAVID P. DOBSON JOHN P. BRODHOLT LIDUNKA VOČADLO WILSON A. CRICHTON 《Molecular physics》2013,111(10):773-777
Experiments have been performed at 5 GPa on liquid Fe-FeS in order to determine Fe and S self-diffusivity as a function of temperature. The viscosity of the sample was then obtained using the Stokes-Einstein relation. The results are in excellent agreement with previous experiments where the viscosity of a material of the same composition under similar conditions was measured directly. These results support high, near-metallic, values of diffusivity and low viscosity in liquid Fe-S up to a few hundred K above the eutectic temperature, in contrast with some previous studies. Moreover, these results fully confirm the validity of the Stokes-Einstein relation between viscosity and diffusion coefficients for Fe0.61S0.39. 相似文献
95.
96.
Numerical Solution of Volterra Integral Equations with Continuous or Discontinuous Terms 总被引:1,自引:0,他引:1
Convergence criteria are given for the numerical solution ofVolterra integral equations with and without discontinuous terms.Several numerical methods are compared. 相似文献
97.
98.
DAVID A. YOUNGS 《Photochemistry and photobiology》1975,21(2):139-139
99.
Structure indices for multidimensional systems 总被引:1,自引:0,他引:1
WOOD JEFFREY; ROGERS ERIC; ROCHA PAULA; OWENS DAVID H. 《IMA Journal of Mathematical Control and Information》2000,17(3):227-256
The structure indices of a one-dimensional system are an importantset of invariants. In this paper we examine a generalizationof this concept to multidimensional linear systems, which correspondsto the algebraic concept of a Hilbert series. We use the standardtheory of the Hilbert series to explain some of the previousID system-theoretic results. We discuss the computation of nDstructure indices from an initial condition set, and the invariantswhich can be derived from these indices. 相似文献
100.
Molecular mobility is studied in poly(butyl methacrylate) isomers with molecular dynamics simulations in order to understand the role of the side chain steric hindrance on the β and δ relaxation mechanisms. The simulations suggest that in the temperature range studied the δ process is weakly influenced by the α process. Conversely, the β process seems to be significantly changed as compared with the low frequency regime. The results exposed also show evidence that the intramolecular cooperativity is higher in PnBMA than in PtBMA, which, could be related to the distance to the α-β crossover. 相似文献