ONIONSHEL=Onion like spherical shell study

ONIONSHEL=Onion like spherical shell study

Pradeep Bhatia (guest) 24 Oct 2018 12:31

Dear Sir,
I want to investigate the properties using shape parameter ONIONSHEL for three layers with the spherical shape.
So, as given in DDSCAT manual on page no. 21, if SHPAR1 =1, then we have to define NCOMP = 3.
Now, problem is that how to set the thickness or radius of first, second and third layers with shape parameter SHPAR1, SHPAR2, and SHPAR3?
Please give the example with setting the values SHPAR1, SHPAR2, and SHPAR3 to run the ddscat.par file.
I wish you will reply soon and explain it with depth.
Thanking You
Your Sincerely
Bhatia P.

Re: ONIONSHEL=Onion like spherical shell study

draine 24 Oct 2018 20:52

The ONIONSHEL option in DDSCAT is intended for use with a uniaxial anisotropic material like graphite in a spherical shell, but has only been set up to do a single shell with vacuum interior.
If you want multiple shells of anisotropic materials, you will need to write your own code to create a "target file" specifying dipole locations and principal axes of the local dielectric tensor, and read it in using option ANIFRMFIL (see UserGuide sectin 21.2).
For isotropic materials, the option CONELLIPS can be used for two zones (e.g., ellipsoidal shell with vacuum interior), but for three layers you will need to write your own target generator and read the file in with option FROM_FILE (see UserGuide section 21.1).