dda7.3.2.rar_光散射_吸光_散射

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.

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 carried out as

described in Flatau & Draine (2012). DDSCAT 7.3 allows accurate calculations of electromagnetic

scattering from targets with “size parameters” 2πa

rectangular solids, finite cylinders, hexagonal prisms, etc.). Target materials may be both inhomoge-

neous 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 specified orientation of the target relative to the

incident wave, and for specified scattering directions. DDSCAT 7.3 can calculate scattering and absorp-

tion by targets that are periodic in one or two dimensions. DDSCAT 7.3 can calculate and store E and B

throughout a user-specified rectangular volume containing the target. A Fortran-90 code ddpostprocess

scattering calculations. If you publish results calculated using DDSCAT 7.3, please cite relevant pub-

lications describing the methods, e.g., Draine & Flatau (1994), Draine & Flatau (2008), and Flatau &

Draine (2012).

1 Introduction 7

2 Applicability of the DDA 8

3 DDSCAT 7.3 12

6 Compiling and Linking on Unix/Linux Systems 16

8 A Sample Calculation: RCTGLPRSM 21

9 The Parameter File ddscat.par 21

10 Running DDSCAT 7.3 Using the Sample ddscat.par File 26

11 Output Files 27

15 Dielectric Functions 32

16 Calculation of hcos θi, Radiative Force, and Radiation Torque 33

17 Memory Requirements 34

18 Target Geometry: The Target Frame 34

19 Target Orientation 34

20 Orientational Averaging 37