The Experts below are selected from a list of 3297 Experts worldwide ranked by ideXlab platform
Maxim A Yurkin - One of the best experts on this subject based on the ideXlab platform.
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Simulations with DDA Light scattering simulations with the Discrete Dipole Approximation
2020Co-Authors: Maxim A YurkinAbstract:The Discrete Dipole Approximation (DDA) is reviewed, discussing both theoretical and numerical aspects. Existing applications and capabilities of the method are shown, as well as its place among other methods of light scattering simulation. Finally, remaining challenges are pointed out
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rectangular Dipoles in the Discrete Dipole Approximation
Journal of Quantitative Spectroscopy & Radiative Transfer, 2015Co-Authors: D A Smunev, Patrick C Chaumet, Maxim A YurkinAbstract:Abstract We performed a comprehensive analysis of the extension of the Discrete Dipole Approximation (DDA) to a rectangular cuboid lattice of Dipoles. The theoretical analysis of two different approaches, based either on the point–Dipole interaction or on the integration of Green׳s tensor (IGT), was performed starting with the rigorous integral equation for the electric field. We showed that the expressions for polarizability and interaction terms must strictly conform to each other, which resolves the existing controversy in the literature. Moreover, there are large differences between the spectra of the interaction matrix in the static limit for those DDA formulations. In particular, the point–Dipole formulation leads to unphysical edges of the spectrum that deteriorate the convergence of the iterative solver with increasing refractive index. This severely limits the applicability of point–Dipole DDA formulations with rectangular Dipoles in contrast to the case of cubic Dipoles. We implemented both above formulations in the open-source code ADDA and illustrated their performance on a number of test cases. In particular, we considered a graphene sheet, with thickness much smaller than the wavelength. The use of rectangular Dipoles (with IGT) resulted in up to 100-times decrease of both simulation time and memory requirements, keeping the satisfactory accuracy. Similar improvements are expected for any strongly oblate or prolate particles in which the smallest dimension is much smaller than the wavelength.
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comparison between the pseudo spectral time domain method and the Discrete Dipole Approximation for light scattering simulations
Optics Express, 2012Co-Authors: Lei Bi, Ping Yang, Lee R Panetta, Maxim A YurkinAbstract:The pseudo-spectral time domain (PSTD) and the Discrete Dipole Approximation (DDA) are two popular and robust methods for the numerical simulation of dielectric particle light scattering. The present study compares the numerical performances of the two methods in the computation of the single-scattering properties of homogeneous dielectric spheres and spheroids for which the exact solutions can be obtained from the Lorenz-Mie theory and the T-matrix theory. The accuracy criteria for the extinction efficiency and the phase function are prescribed to be the same for the PSTD and DDA in order that the computational time can be compared in a fair manner. The computational efficiency and applicability of the two methods are each shown to depend on both the size parameter and the refractive index of the scattering particle. For a small refractive index, a critical size parameter, which decreases from 80 to 30 as the refractive index increases from 1.2 to 1.4, exists below which the DDA outperforms the PSTD. For large refractive indices (>1.4), the PSTD is more efficient than the DDA for a wide size parameter range and has a larger region of applicability. Furthermore, the accuracy shown by the two methods in the computation of backscatter, linear polarization, and asymmetry factor is comparable. The comparison was extended to include spheroids with typical refractive indices of ice and dust and similar conclusions were drawn.
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the Discrete Dipole Approximation code adda capabilities and known limitations
Journal of Quantitative Spectroscopy & Radiative Transfer, 2011Co-Authors: Maxim A Yurkin, Alfons G HoekstraAbstract:The open-source code ADDA is described, which implements the Discrete Dipole Approximation (DDA), a method to simulate light scattering by finite 3D objects of arbitrary shape and composition. Besides standard sequential execution, ADDA can run on a multiprocessor distributed-memory system, parallelizing a single DDA calculation. Hence the size parameter of the scatterer is in principle limited only by total available memory and computational speed. ADDA is written in C99 and is highly portable. It provides full control over the scattering geometry (particle morphology and orientation, and incident beam) and allows one to calculate a wide variety of integral and angle-resolved scattering quantities (cross sections, the Mueller matrix, etc.). Moreover, ADDA incorporates a range of state-of-the-art DDA improvements, aimed at increasing the accuracy and computational speed of the method. We discuss both physical and computational aspects of the DDA simulations and provide a practical introduction into performing such simulations with the ADDA code. We also present several simulation results, in particular, for a sphere with size parameter 320 (100-wavelength diameter) and refractive index 1.05.
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application of the Discrete Dipole Approximation to very large refractive indices filtered coupled Dipoles revived
Physical Review E, 2010Co-Authors: Maxim A Yurkin, Alfons G HoekstraAbstract:We compared three formulations of the Discrete Dipole Approximation (DDA) for simulation of light scattering by particles with refractive indices m = 10+10i, 0.1+i, and 1.6+0.01i. These formulations include the filtered coupled Dipoles (FCD), the lattice dispersion relation (LDR) and the radiative reaction correction. We compared the number of iterations required for the convergence of the iterative solver (proportional to simulation time) and the accuracy of final results. We showed that the LDR performance for m=10+10i is especially bad, while the FCD is a good option for all cases studied. Moreover, we analyzed the detailed structure of DDA errors and the spectrum of the DDA interaction matrix to understand the performance of the FCD. In particular, this spectrum, obtained with the FCD for particles smaller than the wavelength, falls into the bounds, physically implied for the spectrum of the infinite-dimensional integral scattering operator, contrary to two other DDA formulations. Finally, such extreme refractive indices can now be routinely simulated using modern desktop computers using the publicly available ADDA code, which includes an efficient implementation of the FCD.
Piotr J. Flatau - One of the best experts on this subject based on the ideXlab platform.
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user guide for the Discrete Dipole Approximation code ddscat 7 3
arXiv: Computational Physics, 2013Co-Authors: B T Draine, Piotr J. FlatauAbstract:DDSCAT 7.3 is an open-source Fortran-90 software package applying the Discrete Dipole Approximation to calculate scattering and absorption of electromagnetic waves by targets with arbitrary geometries and complex refractive index. The targets may be isolated entities (e.g., dust particles), but may also be 1-d or 2-d periodic arrays of "target unit cells", allowing calculation of absorption, scattering, and electric fields around arrays of nanostructures. The theory of the DDA and its implementation in DDSCAT is presented in Draine (1988) and Draine & Flatau (1994), and its extension to periodic structures in Draine & Flatau (2008), and efficient near-field calculations in Flatau & Draine (2012). DDSCAT 7.3 includes support for MPI, OpenMP, and the Intel Math Kernel Library (MKL). DDSCAT supports calculations for a variety of target geometries. Target materials may be both inhomogeneous and anisotropic. It is straightforward for the user to "import" arbitrary target geometries into the code. DDSCAT automatically calculates total cross sections for absorption and scattering and selected elements of the Mueller scattering intensity matrix for user-specified scattering directions. DDSCAT 7.3 can efficiently calculate E and B throughout a user-specified volume containing the target. This User Guide explains how to use DDSCAT 7.3 to carry out electromagnetic scattering calculations, including use of DDPOSTPROCESS, a Fortran-90 code to perform calculations with E and B at user-selected locations near the target. A number of changes have been made since the last release, DDSCAT 7.2 .
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user guide for the Discrete Dipole Approximation code ddscat 7 2
arXiv: Computational Physics, 2012Co-Authors: B T Draine, Piotr J. FlatauAbstract:DDSCAT 7.2 is a freely available open-source Fortran-90 software package applying the Discrete Dipole Approximation (DDA) to calculate scattering and absorption of electromagnetic waves by targets with arbitrary geometries and complex refractive index. The targets may be isolated entities (e.g., dust particles), but may also be 1-d or 2-d periodic arrays of "target unit cells", which can be used to study absorption, scattering, and electric fields around arrays of nanostructures. The DDA approximates the target by an array of polarizable points. The theory of the DDA and its implementation in DDSCAT is presented in Draine (1988) and Draine & Flatau (1994), and its extension to periodic structures in Draine & Flatau (2008). Efficient near-field calculations are enabled following Flatau & Draine (2012). DDSCAT 7.2 allows accurate calculations of electromagnetic scattering from targets with size parameters 2*pi*aeff/lambda < 25 provided the refractive index m is not large compared to unity (|m-1| < 2). DDSCAT 7.2 includes support for MPI, OpenMP, and the Intel Math Kernel Library (MKL). DDSCAT 7.2 supports calculations for a variety of target geometries (e.g., ellipsoids, regular tetrahedra, rectangular solids, finite cylinders, hexagonal prisms, etc.). Target materials may be both inhomogeneous and anisotropic. It is straightforward for the user to import new target geometries into the code. DDSCAT 7.2 calculates total cross sections for absorption and scattering and selected elements of the Mueller scattering intensity matrix for specified orientation of the target relative to the incident wave, and for specified scattering directions. DDSCAT 7.2 calculates E throughout a user-specified rectangular volume containing the target. A Fortran-90 code READNF to read E and P from files created by DDSCAT 7.2 is included in the distribution.
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fast near field calculations in the Discrete Dipole Approximation for regular rectilinear grids
Optics Express, 2012Co-Authors: Piotr J. Flatau, Bruce T. DraineAbstract:A near-field calculation of light electric field intensity inside and in the vicinity of a scattering particle is discussed in the Discrete Dipole Approximation. A fast algorithm is presented for gridded data. This algorithm is based on one matrix times vector multiplication performed with the three dimensional fast Fourier transform. It is shown that for moderate and large light scattering near field calculations the computer time required is reduced in comparison to some of the other methods.
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Discrete Dipole Approximation for periodic targets theory and tests
Journal of The Optical Society of America A-optics Image Science and Vision, 2008Co-Authors: Bruce T. Draine, Piotr J. FlatauAbstract:The Discrete-Dipole Approximation (DDA) is a powerful method for calculating absorption and scattering by targets that have sizes smaller than or comparable to the wavelength of the incident radiation. The DDA can be extended to targets that are singly or doubly periodic. We generalize the scattering amplitude matrix and the 4×4 Mueller matrix to describe scattering by singly and doubly periodic targets and show how these matrices can be calculated using the DDA. The accuracy of DDA calculations using the open-source code DDSCAT is demonstrated by comparison with exact results for infinite cylinders and infinite slabs. A method for using the DDA solution to obtain fields within and near the target is presented, with results shown for infinite slabs.
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user guide for the Discrete Dipole Approximation code ddscat 7 0
arXiv: Astrophysics, 2008Co-Authors: B T Draine, Piotr J. FlatauAbstract:DDSCAT 7.0 is an open-source Fortran-90 software package applying the Discrete Dipole Approximation to calculate scattering and absorption of electromagnetic waves by targets with arbitrary geometries and complex refractive index. The targets may be isolated entities (e.g., dust particles), but may also be 1-d or 2-d periodic arrays of "target unit cells", allowing calculation of absorption, scattering, and electric fields around arrays of nanostructures. The theory of the DDA and its implementation in DDSCAT is presented in Draine (1988) and Draine & Flatau (1994), and its extension to periodic structures (and near-field calculations) in Draine & Flatau (2008). DDSCAT 7.0 includes support for MPI, OpenMP, and the Intel Math Kernel Library (MKL). DDSCAT supports calculations for a variety of target geometries. Target materials may be both inhomogeneous and anisotropic. It is straightforward for the user to "import" arbitrary target geometries into the code. DDSCAT automatically calculates total cross sections for absorption and scattering and selected elements of the Mueller scattering intensity matrix. This User Guide explains how to use DDSCAT 7.0 to carry out electromagnetic scattering calculations. DDfield, a Fortran-90 code DDfield to calculate E and B at user-selected locations near the target, is included in the distribution.
Alfons G Hoekstra - One of the best experts on this subject based on the ideXlab platform.
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the Discrete Dipole Approximation code adda capabilities and known limitations
Journal of Quantitative Spectroscopy & Radiative Transfer, 2011Co-Authors: Maxim A Yurkin, Alfons G HoekstraAbstract:The open-source code ADDA is described, which implements the Discrete Dipole Approximation (DDA), a method to simulate light scattering by finite 3D objects of arbitrary shape and composition. Besides standard sequential execution, ADDA can run on a multiprocessor distributed-memory system, parallelizing a single DDA calculation. Hence the size parameter of the scatterer is in principle limited only by total available memory and computational speed. ADDA is written in C99 and is highly portable. It provides full control over the scattering geometry (particle morphology and orientation, and incident beam) and allows one to calculate a wide variety of integral and angle-resolved scattering quantities (cross sections, the Mueller matrix, etc.). Moreover, ADDA incorporates a range of state-of-the-art DDA improvements, aimed at increasing the accuracy and computational speed of the method. We discuss both physical and computational aspects of the DDA simulations and provide a practical introduction into performing such simulations with the ADDA code. We also present several simulation results, in particular, for a sphere with size parameter 320 (100-wavelength diameter) and refractive index 1.05.
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application of the Discrete Dipole Approximation to very large refractive indices filtered coupled Dipoles revived
Physical Review E, 2010Co-Authors: Maxim A Yurkin, Alfons G HoekstraAbstract:We compared three formulations of the Discrete Dipole Approximation (DDA) for simulation of light scattering by particles with refractive indices m = 10+10i, 0.1+i, and 1.6+0.01i. These formulations include the filtered coupled Dipoles (FCD), the lattice dispersion relation (LDR) and the radiative reaction correction. We compared the number of iterations required for the convergence of the iterative solver (proportional to simulation time) and the accuracy of final results. We showed that the LDR performance for m=10+10i is especially bad, while the FCD is a good option for all cases studied. Moreover, we analyzed the detailed structure of DDA errors and the spectrum of the DDA interaction matrix to understand the performance of the FCD. In particular, this spectrum, obtained with the FCD for particles smaller than the wavelength, falls into the bounds, physically implied for the spectrum of the infinite-dimensional integral scattering operator, contrary to two other DDA formulations. Finally, such extreme refractive indices can now be routinely simulated using modern desktop computers using the publicly available ADDA code, which includes an efficient implementation of the FCD.
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accuracy of the Discrete Dipole Approximation for simulation of optical properties of gold nanoparticles
Journal of Nanophotonics, 2010Co-Authors: Maxim A Yurkin, David De Kanter, Alfons G HoekstraAbstract:We studied the accuracy of the Discrete Dipole Approximation (DDA) for simulations of absorption and scattering spectra by gold nanoparticles (spheres, cubes, and rods ranging in size from 10 to 100 nm). We varied the Dipole resolution and applied two DDA formulations, employing the standard lattice dispersion relation (LDR) and the relatively new filtered coupled Dipoles (FCD) approach. The DDA with moderate Dipole resolutions is sufficiently accurate for scattering efficiencies or positions of spectral peaks, but very inaccurate for e.g. values of absorption efficiencies in the near-IR. To keep relative errors of the latter within 10% about 10 7 Dipoles per sphere are required. Surprisingly, errors for cubes are about 10 times smaller than that for spheres or rods, which we explain in terms of shape errors. The FCD is generally more accurate and leads to up to 2 times faster computations than the LDR. Therefore, we recommend FCD as the DDA formulation of choice for gold and other metallic nanoparticles.
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systematic comparison of the Discrete Dipole Approximation and the finite difference time domain method for large dielectric scatterers
Optics Express, 2007Co-Authors: Maxim A Yurkin, Alfons G Hoekstra, R S Brock, Jun Q LuAbstract:We compare the Discrete Dipole Approximation (DDA) and the finite difference time domain (FDTD) method for simulating light scattering of spheres in a range of size parameters x up to 80 and refractive indices m up to 2. Using parallel implementations of both methods, we require them to reach a certain accuracy goal for scattering quantities and then compare their performance. We show that relative performance sharply depends on m. The DDA is faster for smaller m, while the FDTD for larger values of m. The break-even point lies at m=1.4. We also compare the performance of both methods for a few particular biological cells, resulting in the same conclusions as for optically soft spheres.
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the Discrete Dipole Approximation an overview and recent developments
Journal of Quantitative Spectroscopy & Radiative Transfer, 2007Co-Authors: Maxim A Yurkin, Alfons G HoekstraAbstract:We present a review of the Discrete Dipole Approximation (DDA), which is a general method to simulate light scattering by arbitrarily shaped particles. We put the method in historical context and discuss recent developments, taking the viewpoint of a general framework based on the integral equations for the electric field. We review both the theory of the DDA and its numerical aspects, the latter being of critical importance for any practical application of the method. Finally, the position of the DDA among other methods of light scattering simulation is shown and possible future developments are discussed.
B T Draine - One of the best experts on this subject based on the ideXlab platform.
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user guide for the Discrete Dipole Approximation code ddscat 7 3
arXiv: Computational Physics, 2013Co-Authors: B T Draine, Piotr J. FlatauAbstract:DDSCAT 7.3 is an open-source Fortran-90 software package applying the Discrete Dipole Approximation to calculate scattering and absorption of electromagnetic waves by targets with arbitrary geometries and complex refractive index. The targets may be isolated entities (e.g., dust particles), but may also be 1-d or 2-d periodic arrays of "target unit cells", allowing calculation of absorption, scattering, and electric fields around arrays of nanostructures. The theory of the DDA and its implementation in DDSCAT is presented in Draine (1988) and Draine & Flatau (1994), and its extension to periodic structures in Draine & Flatau (2008), and efficient near-field calculations in Flatau & Draine (2012). DDSCAT 7.3 includes support for MPI, OpenMP, and the Intel Math Kernel Library (MKL). DDSCAT supports calculations for a variety of target geometries. Target materials may be both inhomogeneous and anisotropic. It is straightforward for the user to "import" arbitrary target geometries into the code. DDSCAT automatically calculates total cross sections for absorption and scattering and selected elements of the Mueller scattering intensity matrix for user-specified scattering directions. DDSCAT 7.3 can efficiently calculate E and B throughout a user-specified volume containing the target. This User Guide explains how to use DDSCAT 7.3 to carry out electromagnetic scattering calculations, including use of DDPOSTPROCESS, a Fortran-90 code to perform calculations with E and B at user-selected locations near the target. A number of changes have been made since the last release, DDSCAT 7.2 .
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user guide for the Discrete Dipole Approximation code ddscat 7 2
arXiv: Computational Physics, 2012Co-Authors: B T Draine, Piotr J. FlatauAbstract:DDSCAT 7.2 is a freely available open-source Fortran-90 software package applying the Discrete Dipole Approximation (DDA) to calculate scattering and absorption of electromagnetic waves by targets with arbitrary geometries and complex refractive index. The targets may be isolated entities (e.g., dust particles), but may also be 1-d or 2-d periodic arrays of "target unit cells", which can be used to study absorption, scattering, and electric fields around arrays of nanostructures. The DDA approximates the target by an array of polarizable points. The theory of the DDA and its implementation in DDSCAT is presented in Draine (1988) and Draine & Flatau (1994), and its extension to periodic structures in Draine & Flatau (2008). Efficient near-field calculations are enabled following Flatau & Draine (2012). DDSCAT 7.2 allows accurate calculations of electromagnetic scattering from targets with size parameters 2*pi*aeff/lambda < 25 provided the refractive index m is not large compared to unity (|m-1| < 2). DDSCAT 7.2 includes support for MPI, OpenMP, and the Intel Math Kernel Library (MKL). DDSCAT 7.2 supports calculations for a variety of target geometries (e.g., ellipsoids, regular tetrahedra, rectangular solids, finite cylinders, hexagonal prisms, etc.). Target materials may be both inhomogeneous and anisotropic. It is straightforward for the user to import new target geometries into the code. DDSCAT 7.2 calculates total cross sections for absorption and scattering and selected elements of the Mueller scattering intensity matrix for specified orientation of the target relative to the incident wave, and for specified scattering directions. DDSCAT 7.2 calculates E throughout a user-specified rectangular volume containing the target. A Fortran-90 code READNF to read E and P from files created by DDSCAT 7.2 is included in the distribution.
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user guide for the Discrete Dipole Approximation code ddscat 7 0
arXiv: Astrophysics, 2008Co-Authors: B T Draine, Piotr J. FlatauAbstract:DDSCAT 7.0 is an open-source Fortran-90 software package applying the Discrete Dipole Approximation to calculate scattering and absorption of electromagnetic waves by targets with arbitrary geometries and complex refractive index. The targets may be isolated entities (e.g., dust particles), but may also be 1-d or 2-d periodic arrays of "target unit cells", allowing calculation of absorption, scattering, and electric fields around arrays of nanostructures. The theory of the DDA and its implementation in DDSCAT is presented in Draine (1988) and Draine & Flatau (1994), and its extension to periodic structures (and near-field calculations) in Draine & Flatau (2008). DDSCAT 7.0 includes support for MPI, OpenMP, and the Intel Math Kernel Library (MKL). DDSCAT supports calculations for a variety of target geometries. Target materials may be both inhomogeneous and anisotropic. It is straightforward for the user to "import" arbitrary target geometries into the code. DDSCAT automatically calculates total cross sections for absorption and scattering and selected elements of the Mueller scattering intensity matrix. This User Guide explains how to use DDSCAT 7.0 to carry out electromagnetic scattering calculations. DDfield, a Fortran-90 code DDfield to calculate E and B at user-selected locations near the target, is included in the distribution.
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Discrete Dipole Approximation with polarizabilities that account for both finite wavelength and target geometry
Journal of The Optical Society of America A-optics Image Science and Vision, 2004Co-Authors: Matthew J Collinge, B T DraineAbstract:The Discrete-Dipole Approximation (DDA) is a powerful method for calculating absorption and scattering by targets that have sizes smaller than or comparable with the wavelength of the incident radiation. We present a new prescription—the surface-corrected-lattice-dispersion relation (SCLDR)—for assigning the Dipole polarizabilities while taking into account both target geometry and finite wavelength. We test the SCLDR in DDA calculations for spherical and ellipsoidal targets and show that for a fixed number of Dipoles, the SCLDR prescription results in increased accuracy in the calculated cross sections for absorption and scattering. We discuss extension of the SCLDR prescription to irregular targets.
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user guide for the Discrete Dipole Approximation code ddscat 6 1
arXiv: Astrophysics, 2004Co-Authors: B T Draine, Piotr J. FlatauAbstract:DDSCAT 6.1 is a freely available software package which applies the “Discrete Dipole Approximation” (DDA) to calculate scattering and absorption of electromagnetic waves by targets with arbitrary geometries and complex refractive index. The DDA approximates the target by an array of polarizable points. DDSCAT 6.1 allows accurate calculations of electromagnetic scatteri ng from targets with “size parameters”2πaeff/λ < 15 provided the refractive index m is not large compared to unity (|m−1| < 2). DDSCAT 6.1 includes the option of using the FFTW (Fastest Fourier Transform in the West) package. DDSCAT 6.1 also includes support forMPI (Message Passing Interface), permitting parallel calcula tions on multiprocessor systems. We also make available a “plain” distribution of DDSCAT 6.1 that does not include support for MPI, FFTW, or netCDF, but is much simpler to install than the full distribution. The DDSCAT package is written in Fortran and is highly portable. The program supports calculations for a variety of target geometries (e.g., ellipsoid s, regular tetrahedra, rectangular solids, finite cylinders, hexagonal prisms, etc.). Target materials may be both inhomogeneous and anisotropic. It is straightforward for the user to “import” arbitrary target g eometries into the code, and relatively straightforward to add new target generation capability to the package. DDSCAT automatically calculates total cross sections for absorption and scattering and selected e lements of the Mueller scattering intensity matrix for specified orientation of the target relative to th e incident wave, and for specified scattering directions.
Juan Carlos Cuevas - One of the best experts on this subject based on the ideXlab platform.
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thermal Discrete Dipole Approximation for the description of thermal emission and radiative heat transfer of magneto optical systems
Physical Review B, 2017Co-Authors: Juan Carlos Cuevas, Ricardo Martin Abraham Ekeroth, Antonio GarciamartinAbstract:We present here a generalization of the thermal Discrete Dipole Approximation (TDDA) that allows us to describe the near-field radiative heat transfer between finite objects of arbitrary shape that exhibit magneto-optical (MO) activity. We also extend the TDDA approach to describe the thermal emission of a finite object with and without MO activity. Our method is also valid for optically anisotropic materials described by an arbitrary permittivity tensor and we provide simple closed formulas for the basic thermal quantities that considerably simplify the implementation of the TDDA method. Moreover, we show that by employing our TDDA approach one can rigorously demonstrate Kirchhoff's radiation law relating the emissivity and absorptivity of an arbitrary MO object. Our work paves the way for the theoretical study of the active control of emission and radiative heat transfer between MO systems of arbitrary size and shape.