Refractive index of the medium

[GoogleCodeExporter]

Implement specifying refractive index of the medium by command line option.
It will simplify application of ADDA to such cases reusing existing files
with refractive index spectra, etc.

Since absorbing refractive index of the medium is fundamentally hard, first
step is to limit the command line argument to real values.

Original issue reported on code.google.com by yurkin on 9 Dec 2009 at 8:49

• Blocked on: Radiation forces in surrounding medium #29

[GoogleCodeExporter]

Original comment by yurkin on 27 Apr 2010 at 4:10

[myurkin]

It is also interesting to look into the possibility of tensorial (anisotropic) epsilon of the medium. But that requires proper formulation of the scattering problem in the first place.

[alkichigin]

It seems to be easy to add support for non-absorbing host medium, let it be called m_h. In our work on EELS (#155) we found that as for now to simulate non-absorbing medium other than vacuum one has to:

• divide -lambda by m_h, so WaveNum variable will contain m_h
• divide -m by m_h, so the polarizability prescription remains valid, as it operates relative refractive index (or permittivity).
  When the -mh parameter is implemented into ADDA, it will be easy to adapt current EELS code to work with general -mh rather than with mh given as a parameter of -beam electron. Plane waves probably won't need any editing at all. All other beams and -surf can log error that -mh currently not supported.

[myurkin]

@Sunmosk

[Sunmosk]

Already added -mhost into ADDA in my local copy. Currently it works for real RI (non-absorbing host medium), but my goal is to add support of complex RI.

[myurkin]

The first operational version (proof-of-principle) for complex RI is available at https://github.com/Sunmosk/adda-complex_freq