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61.
N. A. Anikin A. S. Mendkovich M. B. Kuzminskiy A. M. Andreev 《Russian Chemical Bulletin》2008,57(2):428-430
A new fast computational method for mass calculations of docking complexes by the AM1/PM3 semiempirical methods is proposed.
The computation time is shortened by at least an order of magnitude compared to alternative schemes of quantum chemical calculations.
The root-mean-square deviation of the AM1 calculated energies of formation of complexes from the results obtained by conventional
diagonalization procedure is at most 0.4 kcal mol−1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 418–420, February, 2008. 相似文献
62.
63.
G. Palfinger B. Bitnar H. Sigg E. Müller S. Stutz D. Grützmacher 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):481
In order to obtain a low band gap photocell based on the widely spread silicon technology, e.g. for thermophotovoltaics, SiGe nanostructures can be introduced into a monocrystalline silicon photocell. Beforehand, it is necessary to know the absorption coefficient of the SiGe quantum wells. On a silicon (1 0 0) substrate multiple Si/SiGe quantum well structures were grown by UHV-CVD. The Ge concentration and the well width were used as growth parameters. To obtain significant absorption, the experiment was set up to allow for 200 internal reflections.The total reflection of the light results in a standing electromagnetic wave. The absorption coefficient was obtained from the experimental data taking the geometry and the electric field distribution in the absorbing layer into account. The influence of well width and germanium content on the absorption was investigated with the goal of maximizing the absorption for photons with energies below the band gap energy of silicon. The measurement results are compared with a theoretical model, which takes the band structure of strained SiGe including confinement effects into account. 相似文献
64.
The quantum fluctuations of the stress tensor of a quantum field are discussed, as are the resulting space-time metric fluctuations. Passive quantum gravity is an approximation in which gravity is not directly quantized, but fluctuations of the space-time geometry are driven by stress tensor fluctuations. We discuss a decomposition of the stress tensor correlation function into three parts, and consider the physical implications of each part. The operational significance of metric fluctuations and the possible limits of validity of semiclassical gravity are discussed. 相似文献
65.
The problem on the set-theoretical solutions to the quantum Yang-Baxter equation was presented byDrinfel'd as a main unsolved problem in quantum group theory. The set-theoretical solutions are a natural extensionof the usual (linear) solutions. In this paper, we not only give a further study on some known set-theoretical solutions(the Venkov's solutions), but also find a new kind of set-theoretical solutions which have a geometric interpretation.Moreover, the new solutions lead to the metahomomorphisms in group theory. 相似文献
66.
We review the proof of a conjecture concerning the reality of the spectra of certain PT-symmetric quantum mechanical systems, obtained via a connection between the theories of ordinary differential equations and integrable models. Spectral equivalences inspired by the correspondence are also discussed. 相似文献
67.
Q. H. Liu W. H. Qi T. G. Liu Z. H. Zhu 《International Journal of Theoretical Physics》2003,42(4):783-791
Expectation values of physical quantities in a wave packet involving few stationary states in an infinite square well are calculated. Explicit results show that the expectation values in the classical limit go over to the corresponding classical quantity in the form of the arithmetic mean (in mathematical term, the Fejér's average) of the partial Fourier series converging to the classical quantity. The number of the stationary states is that of the partial Fourer series in the Fejér's average. The quantum uncertainty is then demonstrated to have a classical counterpart. 相似文献
68.
M. I. Dykman D. G. Luchinsky R. Mannella P. V. E. McClintock N. D. Stein N. G. Stocks 《Il Nuovo Cimento D》1995,17(7-8):661-683
Summary We outline the historical development of stochastic resonance (SR), a phenomenon in which the signal and/or the signal-to-noise
ratio in a nonlinear system increase with increasing intensity of noise. We discuss basic theoretical ideas explaining and
describing SR, and we review some revealing experimental data that place SR within the wider context of statistical physics.
We emphasize the close relationship of SR to some effects that are well known in condensed-matter physics.
Paper presented at the International Workshop ?Fluctuations in Physics and Biology: Stochastic Resonance, Signal Processing
and Related Phenomena?, Elba, 5–10 June 1994. 相似文献
69.
Brad M. Rosen Virgil Percec 《Journal of polymer science. Part A, Polymer chemistry》2007,45(21):4950-4964
Atom transfer radical polymerization (ATRP) and single electron‐transfer living radical polymerization (SET‐LRP) both utilize copper complexes of various oxidation states with N‐ligands to perform their respective activation and deactivation steps. Herein, we utilize DFT (B3YLP) methods to determine the preferred ligand‐binding geometries for Cu/N‐ligand complexes related to ATRP and SET‐LRP. We find that those ligands capable of achieving tetrahedral complexes with CuI and trigonal bipyramidal with axial halide complexes with [CuIIX]+ have higher energies of stabilization. We were able to correlate calculated preferential stabilization of [CuIIX]+ with those ligands that perform best in SET‐LRP. A crude calculation of energy of disproportionation revealed that the same preferential binding of [CuIIX]+ results in increased propensity for disproportionation. Finally, by examining the relative energies of the basic steps of ATRP and SET‐LRP, we were able to rationalize the transition from the ATRP mechanism to the SET‐LRP mechanism as we transition from typical nonpolar ATRP solvents to polar SET‐LRP solvents. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4950–4964, 2007 相似文献
70.
Cynthia Kolb Whitney 《Foundations of Physics》2007,37(4-5):788-812
This paper revisits the historical sequence in which some of the major developments of 20th-century physics occurred, and
explores how theories could have turned out differently, if the sequence of developments had been different. It shows how
a delay in founding special relativity theory until after (1) at least one puzzling problem in electromagnetic theory could
be acknowledged, and (2) sat least some of the experimental observations pertinent to the development of quantum mechanics
had become well known, could have resulted in a larger theory that covers both domains in a manner quite different from that
of any of the theories we use today. The revised theory dispenses with a separate postulate introducing Planck’s constant
h, identifying instead a physical mechanism that implies the constant. Some important aspects of quantum chemistry then follow.
Editor, Galilean Electrodynamics, Proceedings of the Natural Philosophy Alliance; Visiting Industry Professor, Tufts University,
retired 相似文献