Near field calculation

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Think of a convenient way to calculate near field in a number of points or
on a grid around the particle. Possibly implement calculation of the
B-field together with E-field.

Original issue reported on code.google.com by yurkin on 26 Nov 2008 at 8:13

• Blocked on: storing dipoles as binary file #90

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Original comment by yurkin on 23 Nov 2009 at 2:54

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An external program to compute the near field on an arbitrary set of points
(i.e. not related to the dipole grid) is now available,  see
 http://a-dda.googlecode.com/files/near_field_0_79.zip
or it can obtained from the subversion repository in the directory
misc/near_field.
The nearfield program reads the files generated by adda with the 
options -store_dip_pol -save_geom and an file with a lists of external (i.e. 
outside
the target) points.
The nearfield program is a MPI program.

Original comment by fabio.de...@gmail.com on 24 Nov 2009 at 6:15

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A slightly corrected version of the near_field package is available
http://a-dda.googlecode.com/files/near_field_1_01.tar.gz

Original comment by yurkin on 24 Nov 2009 at 4:36

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See also issue 126 for arbitrary incident beams.

Overall, the goal is to make a general framework (built into the main ADDA 
package) to compute both E and B fields efficiently for a large grids of 
points, using FFT. See e.g. the ddfield program in DDSCAT.

#126

Original comment by yurkin on 14 Jan 2014 at 8:07

• Now blocked on: storing dipoles as binary file #90

[myurkin]

/cc @fabiods

[myurkin]

Robustness of handling shape files for misc/near_field has been improved by #259 (was not compatible with the master branch of adda). Now it also works fine for inhomogeneous particles.

[myurkin]

Other potentially interesting quantities are Poynting vector, field chirality (proportional to Im(E*.H)), and Maxwell's stress tensor.

Also, it should be possible to compute field derivatives - either numerically, as e.g. in the pyGDM, or analytically. The latter is related to #14 (and can be addressed similarly).