Fast real-time convolution algorithm for microwave multiport networks with nonlinear terminations

Chiang, I-Ting; Chew, Weng Cho

doi:10.1109/tcsii.2005.850410

Cited by 16 publications

(1 citation statement)

References 8 publications

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“…In particular, the computational complexity from O(m 3 ) to O[m 2 log 2 2 (m)] can be achieved. 49,50 In the following, we discuss how to use the FFT method in Eq. (60) to illustrate our approach.…”

Section: Numerical Resultsmentioning

confidence: 99%

First-principles investigation of transient dynamics of molecular devices

2012

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Based on the nonequilibrium Green's function (NEGF) and time-dependent density-functional theory (TDDFT), we propose a formalism to study the time-dependent transport behavior of molecular devices from first principles. While this approach is equivalent to the time-dependent wave-function approach within TDDFT, it has the advantage that the scattering states and bound states are treated on equal footing. Furthermore, it is much easier to implement our approach numerically. Different from the time-dependent wave-function [ψ(t,E)] approach, our formalism is in the time space [G r (t,t )], making this method superior in the time-dependent transport problem with many subbands in the transverse direction. For the purpose of numerical implementation on molecular devices, a computational tractable numerical scheme is discussed in detail. We have applied our formalism to calculate the transient current of two molecular devices Al-1,4-dimethylbenzene-Al and Al-benzene-Al from first principles. In the calculation, we have gone beyond the wideband limit and used the adiabatic local density approximation that was used within TDDFT. It is known that when the wideband limit is abandoned, the boundary condition of the transport problem is non-Markovian, resulting in a memory term in the effective Hamiltonian of the scattering region. To overcome the computational complexity due to the memory term, we have employed a fast algorithm to speed up the calculation and reduced the CPU time from the scaling N 3 to N 2 log 2 2 (N ) for the steplike pulse, where N is the number of time steps in the time evolution of the Green's function. To ensure the accuracy of our method, we have done a benchmark transient calculation on an atomic junction using a time-dependent wave-function approach within TDDFT in momentum space, which agrees very well with the result from our method.

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Section: Numerical Resultsmentioning

confidence: 99%

First-principles investigation of transient dynamics of molecular devices

2012

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Finite Element Formulation

Jin

Riley

2008

Finite Element Analysis of Antennas and Arrays

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An incremental and piecewise linear finite element theory is developed for the large displacement, large strain regime with particular reference to elastic-plastic behavior in metals. The resulting equations, though more complex, are in a similar form to those previously developed for large displacement, small strain problems, the only additional term being an initial load stiffness matrix which is dependent on current loads. This similarity in form means that existing nonlinear general purpose programs may easily be extended to include finite strains. A large displacement, small strain formulation (as applicable to problems of structural stability) is obtained from this theory by assuming that changes in length of line elements and relative rotation of orthogonal line elements arc negligible compared to unity. The simplified equations are in essential agreement with previous formulations in the literature. The only difference which is observed is the persistence of the initial load stiffness matrix, which may be significant in some cases.

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Modeling of doubly lossy and dispersive media with the time‐domain finite‐element dual‐field domain‐decomposition algorithm

Jin

2012

Int J Numerical Modelling

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SUMMARY A numerical scheme is presented for the time‐domain finite‐element modeling of an electrically and magnetically lossy and dispersive medium in the dual‐field domain‐decomposition method. Existing approaches for modeling doubly lossy and dispersive media are extended to the dual‐field case, yielding a general dual‐field domain‐decomposition scheme for modeling large‐scale electromagnetic problems involving such media. A quantitative analysis is performed to estimate the error induced by the modeling of medium dispersion. Copyright © 2012 John Wiley & Sons, Ltd.

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Fast real-time convolution algorithm for microwave multiport networks with nonlinear terminations

Cited by 16 publications

References 8 publications

First-principles investigation of transient dynamics of molecular devices

First-principles investigation of transient dynamics of molecular devices

Finite Element Formulation

Modeling of doubly lossy and dispersive media with the time‐domain finite‐element dual‐field domain‐decomposition algorithm

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