2 particle systems

[Pingwie]

Hello,

I want to know if this ADDA calculates the 2 particle systems like,
"Noble Metal Nanoparticle Pairs: Effect of Medium for Enhanced
Nanosensing"
Nano Lett., 2008, 8 (12), pp 4347-4352
"Calibration of Dynamic Molecular Rulers Based on Plasmon Coupling
between Gold Nanoparticles"
Nano Lett., 2005, 5 (11), pp 2246–2252

I just started to use ADDA and did following the tutorial.
So, can I calculate the 2 particle system and plasmon redshift?

Regards,
Pingwie

[Maxim Yurkin]

Dear Pingwie,

I haven't read the papers that you mentioned, so I am not sure exactly what kind of particle you are interested in.
However, the short answer is: ADDA is definitely suitable for this task. But there are two issues that should be considered:

1) ADDA has a limited set of predefined shapes. In the stable version (0.79) there are no 2 particle systems defined. In
the current version (0.80a5) there are predefined shapes for two identical spheres (or two-layered spheres) separated by
some distance (shapes "bisphere" and "bicoated"). However the latter version is potentially unstable and you should
obtain it from Subversion repository and compile yourself.
If your scattering problem do not fit into this set of predefined shapes, you have to construct the "shape file". It is
straightforward to do it (there is extensive description in the manual), but requires extra effort.

2) ADDA computational requirements will increase with separation distance, because ADDA includes all empty space between
2 particles into the computation. This is a common problem for all DDA programs and is not expected to be solved soon
(also there are certain ideas http://code.google.com/p/a-dda/issues/detail?id=48). But with modern computers this should
not be a large problem.

I hope this answers your question, but feel free to specify it further, if needed.

Best regards,
Maxim.