Defining a scatterer

[hazraatrayee]

I am new to ADDA. As a first step I want to run the code for a spherical nanoparticle with radius 8nm i.e. 0.008um. I have some queries regarding defing such scatterer.

1. Is this radius is r_ef i.e. effective eadius or it is x?
2. How can I define such scattere in terms of dpl, nx, Dx?
3. Other than fine tuning to get appropriate effective size what is the basic thumb rule to define a such scatterer?

I have gone through FAQ and tutorial, but it is not clear to me how the radius is 2Π by the command adda –grid 16 –m 1.5 0 –size 1 –lambda 1

Please help so that I can proceed to calculations.

[myurkin]

1. It is the effective radius r_ef, so x = k*r_ef
2. Read section 6.2 of the manual
3. For nanoparticles the safest is to manually set a grid to a rather large value, e.g.

   adda -size 0.016 -lambda ... -grid 32 -m ... 

The line from tutorial that you mentioned sets the diameter (1) equals to wavelength (1). If -lambda 1 is omitted, then wavelength would be equal to 2Π and, thus, not equal to diameter anymore.

[hazraatrayee]

Thank you very much Sir, for your kind reply.

So basically for an example if I have a particle with diameter of say 20nm, the command will be like:

adda -size 0.02 -lambda ... -grid 32 -m ...

And by the grid I am specifying n_x. With higher n_x the size of each dipole will decrease and it will improve the shape accuracy. Is that so?

[myurkin]

Yes, that is correct.

[hazraatrayee]

Thank you very much Sir.