Results 1 - 10 of 12205
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[en] This paper summarizes and extends results from a series of recent investigations of atomic scale friction, in which an ultra-low effective mass and a corresponding thermal delocalization of the contact play a dominant role. A rich variety of physically different regimes of friction concerned with the contact delocalization are analyzed in a systematic way and visualized by advanced numerical calculations. The results shed an essentially new light on what is actually measured in friction force microscopy and suggest the necessity to reinterpret many seemingly standard experiments. Even more importantly, our results can possibly be extended to the asperities that establish the contact between two sliding bodies thus predicting a much more pronounced role of thermally driven dynamics in macroscopic sliding than has ever been imagined. The paper is supplied with a detailed introduction to the subject, aimed at a general physical audience
[en] We show that the new relation between master integrals recently obtained in M.Yu. Kalmykov and B.A. Kniehl (2011) can be reproduced using the integration-by-parts technique implemented with an effective mass. In fact, this relation is recovered as a special case of a whole family of new relations between master integrals.
[en] Assuming a schematic form of the nucleon effective mass as a function of nuclear excitation energy and mass, we provide a simple explanation for understanding the experimentally observed mass dependence of the nuclear caloric curve. It is observed that the excitation energy at which the caloric curve enters into a plateau region could be sensitive to the nuclear mass evolution of the effective nucleon mass
[en] We develop an analogy between spontaneous symmetry breaking in quantum chromodynamics and electroweak theory, from which it follows that effective quark masses occur through interactions of quarks with quark-antiquark pairs of sea quarks. We estimate the strong quark radius and energy at which quarks can be observed, free of confinement.(author)
[en] In this work, the stability, mechanical properties, mechanical anisotropy properties, electronic properties and effective mass anisotropy of C2/m-20 Si1-xGex (x = 0, 0.2, 0.4, 0.6, 0.8, 1) are studied through ab initio calculations. Effective mass is an important index to measure the transport properties of semiconductor. The analysis of effective mass anisotropy can provide theoretical basis for the design of crystal orientation of semiconductor devices. By increasing the discussion of the differentiability of the E-k relation of carriers, the rationality of its Taylor expansion is determined to judge the feasibility of the effective mass tensor. Avoiding the misuse of the effective mass tensor enables researchers to obtain more accurate and reliable results in the analysis of the effective mass anisotropy. Through the combination of the effective mass tensor method and the traversal method, the lowest effective mass can be quickly found while the amount of calculation is greatly reduced. This is of great significance for research on the carrier transport properties of materials. Extremely low hole effective masses is found in a novel phase of germanium with a hole effective mass of 0.017 m 0 in  direction. This indicates that C2/m-Ge20 has a very high carrier mobility in  direction which have a great impact on the field of electronic devices. (paper)
[en] Stationary states of neutrino are obtained and analyzed as a neutron with vanishing mass in the field of a longitudinal linearly polarized wave plus a transverse linearly polarized wave and in the field of a plane wave with circular polarization. The neutrino 'effective' mass is calculated. 3 refs
[en] The effective mass and spectrum of Landau levels are calculated for the valence band of a HgTe/HgCdTe quantum well with an inverted band structure in the quasi-classical “extremum loop” model. The Landau-level fan of the valence band in the semimetallic phase starts at B = 0 from the energy corresponding to that of the lateral maxima of this band and is overlapped with the Landau-level fan of the conduction band.