Discrete Dipole Approximation (DDA) is an important tool in plasmonics research. Using DDA, one can calculate scattering properties of nanoparticles at various wavelengths, polarizations and surrounding medium. The specialty of DDA is that one can calculate scattering properties of irregular shape particles (particles other than spheroids). DDA is based on representing a particle into a set of interacting dipoles and solving their dipole moments such that they are all self-conistent with each other and are linked by far-field and near-field interactions. Once these dipole moments are calculated, they can be used to calculate scattering properties such as scattering efficiency, absorption efficiency and extinction efficiency. Not only efficiencies, one can also calculate electric field and magnetic field at an interested wavelength of incident light. More information on DDA can be found in this review paper.

There are various codes that have implemented the discrete dipole approximation method. My favorite implentation is DDSCAT. DDSCAT is a free and easy to learn code. You can get more information on downloading and installing DDSCAT here.

Here, I have used DDSCAT to calculate the electric field near the vicinity of a 60 nm gold nanoparticle in water at localized surface plasmon resonance (532 nm). Note the large electric field at the edges of the nanoparticle and dipolar field due to plasmon resonance.

UPDATE: Many of my readers were interested in the simulation files. You can find my project file here. **Note that electric fields were calculated using DDSCAT7.1 (ddscat7.2 uses totally different method to calculate electric field)**. The folder contains details for calculating and plotting the electric field around a sphere in xy plane, where light is polarized in y direction and propagting in x direction. But this could be extended to other geometries and other planes of interest. Follow these steps: 1) Read the flowchart.ppt to understand the problem of interest and the work flow 2) compile the ddscat7.1 source_code on linux or windows with cygwin 3) get hold of octave/matlab for running the efield part.

Hi,

I am Raju from India. I like to know about a tool which is useful for plotting the electric field result generated by DDSCAT.

Dear sir,I am interested to get if possible your meep code for SP. Would you please mail the meep code to my E-mail? My e-mail is hosophy@gmail.com. Thank you very much.

Yours sincerely,sophy.

Dear Dr Bala,

At the present time, I am performing DDSCAT calculations on metallic nanoparticles and I am interested in visualizing elctric field distributions and above all ,surface charge distributions.

( I am aware of the DDpol and DDField subroutines).

Could you give me some information or tricks about this point?

Thank you in advance.

Best regards

Dr Michel Pellarin

Hi I’m trying to use the subroutine ddpol, and as result I’m getting the same values for the polarization for all points I choose.

Do you have any idea on what I’m doing wrong?

Thanks in advance,

Diego

Hey Bala, I really liked the simulations on you website. Would like to be in contact for a while for my simulation work on SERS. I don’t require the code but would like to get the required input to write it and get acquainted to it.

You have done terrific work on simulation that I would say!!!

Thanks

Deepak

Sir ,

I have performed DDSCAT simulations for Au,Al and Ag nanoparticles.

I want to visualize electric field pattern.Please give me information about how to visualize electric field or code used to generate the images on your website.

Thanking you in advance.

Now you can download the project file. Click at the link in the post.

Hi

I am Davood from Iran,

Thank you so much because of your rar file in which it was consist of full information about how we can plot E-Field pattern of a nanosphere.

Best.

Hiiii

Could you help me regarding MATLAB version of the software???

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Hi

I am work with ddscat7.2. I plot nearfield of nanoparticles. Now I want plot polarization direction in each point. In user guide of ddscat written to see the information of wxxxryyykzzz.poln shoule use writepol.f.

but I cant compile wxxxryyykzzz.poln .Could you help me.

Thank you in advance.