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81.
Christof Külske 《Journal of statistical physics》2003,112(5-6):1079-1108
It is known that the joint measures on the product of spin-space and disorder space are very often non-Gibbsian measures, for lattice systems with quenched disorder, at low temperature. Are there reflections of this non-Gibbsianness in the corresponding mean-field models? We study the continuity properties of the conditional probabilities in finite volume of the following mean field models: (a) joint measures of random field Ising, (b) joint measures of dilute Ising, (c) decimation of ferromagnetic Ising. The conditional probabilities are functions of the empirical mean of the conditionings; so we look at the large volume behavior of these functions to discover non-trivial limiting objects. For (a) we find (1) discontinuous dependence for almost any realization and (2) dependence of the conditional probabilities on the phase. In contrast to that we see continuous behavior for (b) and (c), for almost any realization. This is in complete analogy to the behavior of the corresponding lattice models in high dimensions. It shows that non-Gibbsian behavior which seems a genuine lattice phenomenon can be partially understood already on the level of mean-field models. 相似文献
82.
83.
The Car-Parrinello method for ab-initio molecular dynamics avoids the explicit minimization of energy functionals given by
functional density theory in the context of the quantum adiabatic approximation (time-dependent Born-Oppenheimer approximation).
Instead, it introduces a fictitious classical dynamics for the electronic orbitals. For many realistic systems this concept
allowed first-principle computer simulations for the first time. In this paper we study the quantitative influence of the involved parameter , the fictitious electronic mass of the method. In particular, we prove by use of a carefully chosen two-time-scale asymptotics
that the deviation of the Car-Parrinello method from the adiabatic model is of order – provided one starts in the ground state of the electronic system and the electronic excitation spectrum satisfies a certain
non-degeneracy condition. Analyzing a two-level model problem we prove that our result cannot be improved in general.
Received June 14, 1996 相似文献
84.
85.
Christof Litwin 《Physics letters. [Part B]》1979,80(3):236-238
The contribution of the multibubble insertions in the photon propagator to the anomalous magnetic moment of the electron is reexamined. Using the asymptotic form of the photon propagator one finds a softer singularity than that found in a recent analysis. 相似文献
86.
Coriani S Marchesan D Gauss J Hättig C Helgaker T Jørgensen P 《The Journal of chemical physics》2005,123(18):184107
The performance of the standard hierarchy of ab initio models--that is, Hartree-Fock theory, second-order Moller-Plesset theory, coupled-cluster singles-and-doubles theory, and coupled-cluster singles-doubles-approximate-triples theory--in combination with correlation-consistent basis sets is investigated for equilibrium geometries of molecules containing second-row elements. From an analysis on a collection of 31 molecules (yielding statistical samples of 41 bond distances and 13 bond angles), the statistical errors (mean deviation, mean absolute deviation, standard deviation, and maximum absolute deviation) are established at each level of theory. The importance of core correlation is examined by comparing calculations in the frozen-core approximation with calculations where all electrons are correlated. 相似文献
87.
Scattering spherical voids in nanocrystalline TiO2- enhancement of efficiency in dye-sensitized solar cells 总被引:1,自引:0,他引:1
Hore S Nitz P Vetter C Prahl C Niggemann M Kern R 《Chemical communications (Cambridge, England)》2005,(15):2011-2013
Spherical voids as light scattering centers in nanocrystalline TiO2 films were realized with polystyrene particles of diameter 400 nm, thus enhancing the photovoltaic performance by 25% on large areas, as well as providing an indication that these films can be used with electrolytes of higher viscosity. 相似文献
88.
89.
We study the multiplicative properties of the dual of Lusztig's semicanonical basis. The elements of this basis are naturally indexed by the irreducible components of Lusztig's nilpotent varieties, which can be interpreted as varieties of modules over preprojective algebras. We prove that the product of two dual semicanonical basis vectors ρZ′ and ρZ″ is again a dual semicanonical basis vector provided the closure of the direct sum of the corresponding two irreducible components Z′ and Z″ is again an irreducible component. It follows that the semicanonical basis and the canonical basis coincide if and only if we are in Dynkin type An with n?4. Finally, we provide a detailed study of the varieties of modules over the preprojective algebra of type A5. We show that in this case the multiplicative properties of the dual semicanonical basis are controlled by the Ringel form of a certain tubular algebra of type (6,3,2) and by the corresponding elliptic root system of type . 相似文献
90.