排序方式: 共有29条查询结果,搜索用时 15 毫秒
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E. Krotscheck R. E. Zillich 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):113-116
We present a microscopic theory and results of atom
scattering calculations to determine the dispersion of surface modes
(ripplons) of superfluid helium-4 nanodroplets, expanding previous
work [J. Chem. Phys. 115, 10161 (2001)]. A quantum transport formalism is
adapted to the many-body scattering problem, yielding both elastic and
inelastic fluxes. We demonstrate that, in analogy to the dynamic
structure function S(k,ω) obtained from neutron scattering, a
dynamic structure function σ(k,ω) can be obtained from
3He scattering. The 3He dynamic structure function
σ(k,ω) is sensitive to surface dynamics,
whereas the neutron dynamic structure function S(k,ω) is
dominated by bulk-like excitations, in particular by rotons.
Unlike for neutron-scattering, the total inelastic cross section for
atom-scattering on 4He nanodroplets is large which we believe makes
experimental detection feasible. We also show that scattering identical particles, i.e. 4He atoms, does not provide
information about the dispersion of surface modes. Instead,
inelastically scattered 4He atoms preferably lose roughly half
their energy. 相似文献
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For l, an -triangulation F of a planar domain is such that,for every T F, there holds 1 RT/2rT , where RT (resp. rT)denotes the radius of the circumscribed (resp. inscribed) circleof the triangle T. When T is varying in F the centre of itsinscribed circle is varying in a compact interior to T and itsorthogonal projections on the sides are varying in compact intervalsinterior to these sides. Precise results are given about thesizes of these compacts and are used for the computation oferror constants in the problem of Hermite interpolation by Powell-Sabinquadratic finite elements, bringing to the fore their dependenceon the parameter . 相似文献
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Rotational absorption spectra of acetylene in superfluid 4He calculated using a path-integral correlation function approach are seen to result in an anomalously large distortion constant in addition to a reduced rotational constant, with values in excellent agreement with recent experiments. Semianalytic treatment of the dynamics with a combined correlated basis function-diffusion Monte Carlo method reveals that this anomalous behavior is due to strong coupling of the higher rotational states of the molecule with the roton and maxon excitations of 4He, and the associated divergence of the 4He density of states in this region. 相似文献
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Guillon G Zanchet A Leino M Viel A Zillich RE 《The journal of physical chemistry. A》2011,115(25):6918-6926
An analytical potential energy surface for a rigid Rb? in the 3Σ(u)? state interacting with one helium atom based on accurate ab initio computations is proposed. This 2-dimensional potential is used, together with the pair approximation approach, to investigate Rb? attached to small helium clusters He(N) with N = 1-6, 12, and 20 by means of quantum Monte Carlo studies. The limit of large clusters is approximated by a flat helium surface. The relative orientation of the dialkali axis and the helium surface is found to be parallel. Dynamical investigations of the pendular and of the in-plane rotation of the rigid Rb? molecule on the surface are presented. 相似文献