271,030 research outputs found

    A peridynamic theory for linear elastic shells

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    A state-based peridynamic formulation for linear elastic shells is presented. The emphasis is on introducing, possibly for the first time, a general surface based peridynamic model to represent the deformation characteristics of structures that have one physical dimension much smaller than the other two. A new notion of curved bonds is exploited to cater for force transfer between the peridynamic particles describing the shell. Starting with the three dimensional force and deformation states, appropriate surface based force, moment and several deformation states are arrived at. Upon application on the curved bonds, such states beget the necessary force and deformation vectors governing the motion of the shell. Correctness of our proposal on the peridynamic shell theory is numerically assessed against static deformation of spherical and cylindrical shells and flat plates

    Ground and excited states of Li^-, Be^- through a density-based approach

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    Density functional calculations are performed for ground [He]2s2^2 1^1Se^e, and three metastable bound excited states, 1s2s2p2^2 5^5Pe^e, 1s2p3^3 5^5So^o, 1s2s2p3p 5^5Pe^e of Li^- and [He]2s2p2^2 4^4Pe^e, [He]2p3^3 4^4So^o, 1s2s2p3^3 6^6So^o of Be^- each. The work-function-based exchange potential is used, while the correlation effects are included by employing the Lee-Yang-Parr potential. The relevant nonrelativistic KS equation is solved by means of a generalized pseudospectral discretization scheme offering nonuniform and optimal spatial grid. Computed total energies, radial densities, selected density moments, as well as two transition wavelengths (1s2s2p2^2 5^5Pe^e \to1s2p3^3 5^5So^o of Li^-, [He]2s2p2^2 4^4Pe^e \to [He]2p3^3 4^4So^o of Be^-) show reasonably good agreement with the available theoretical and experimental data. The term energies show an absolute deviation of 0.007--0.171% with the largest deviation being observed for the even-parity 5^5P state of Li^-. The transition wavelengths of Li^-, Be^- are calculated within 0.891 and 0.438% of the experimental values. This offers a simple practical route towards accurate reliable calculation of excited states of anions within density functional theory.Comment: 12 pages, 35 ref

    Time dependent nonclassical properties of even and odd nonlinear coherent states

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    We construct even and odd nonlinear coherent states of a parametric oscillator and examine their nonclassical properties.It has been shown that these superpositions exhibit squeezing and photon antibunching which change with time.Comment: 3 eps figure