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Hello,

I study scattering using DDSCAT7.3.
I have some questions about CYLNDRPBC.
I want to make regolith using CYLNDRPBC, so I wrote shape parameter such like ::60.0 1.0 1 1.0 1.0 .

Then, in the output file 'w000r000k000.sca', there are only two theta values(0, 180)
I want to (0~180)theta value.
How can I do?

CYLNDRPBC : 2-d periodic by bysong (guest), 22 May 2017 08:47

The first step would be to verify that MPI is installed and operational, and what the local "job submission" procedures are on your system (which will include telling MPI how many cores or cpus to use for the calculation).

Have you succeeded running any other code using MPI on your system?

by drainedraine, 17 May 2017 11:49

Hello!

I am executing ddscat as a part of a University Thesis and I am having trouble using MPI for parallel calculations. I have followed all the instructions in the User Guide, having changed all the parameters necessary in both files "ddscat.par" and "Makefile". Once compiled, I am having trouble making the code understand it has to separate itself in different cores: it keeps on calculating everything in a single node. How do I manage to tell the code to run separately? Is there a parameter I should change that I don't know about?

Thank you!

by Javier (guest), 17 May 2017 09:33

Is it possible to calculate the electric field to limit the total volume of nanoparticle plasmon resonance wavelength of not only the wavelength؟

JPBC is an internal variable used by DDSCAT: JPBC=1 for targets that are periodic in one direction, JPBC=2 for targets that are periodic in two directions.
For periodic targets (such as CYLNDRPBC), DDSCAT requires that the scattering directions be specified in the target frame (TFRAME).

Re: scattering directions by drainedraine, 07 May 2017 13:05
draine (guest) 07 May 2017 11:53
in discussion DDSCAT / Report errors » meet a problem? asking for help!

First — please use the current version: ddscat7.3.2
Section 29 of the UserGuide describes what to do.
When you run with NRFLD=1, ddscat will create binary files wxxxryyykzzz.poln
The program ddpostprocess can read these files and write out selected data, such
as the polarizations, in files that can be used by other software, such as VTK.
Please see section 30.1 of the UserGuide.
You may wish to modify DDPOSTPROCESS.f90 to better meet your needs — see section 30.2 of the UserGuide.

by draine (guest), 07 May 2017 11:53
Arezu (guest) 06 May 2017 15:58
in discussion DDSCAT / Report errors » meet a problem? asking for help!

I am work with ddscat7.2. I plot nearfield of nanoparticles. Now I want plot polarization direction in each point.
but I cant compile wxxxryyykzzz.poln .Could you help me

by Arezu (guest), 06 May 2017 15:58
Devender Kumar (guest) 07 Apr 2017 10:22
in discussion DDSCAT / General discussion » target size

i am doing the calculation for nanorod say radius= 12nm and length=48 nm. then actual volume of target(nanorod) is V= pi*radius^2*Length.
and effective radius of equal volume sphere is aeff= (3*V/4*pi)^(1/3)= 17.3 nm. i get only one peak but according to theory we should get two peaks (transverse and Longitudinal ).
Please suggest me how i can choose direction of polarization and shape parameters.
what is relation between shape parameters and effective radius.

by Devender Kumar (guest), 07 Apr 2017 10:22

You have to provide a FULL name of where the DDSCAT executable is. Otherwise you can copy (using cp command) this executable to your test folder. Piotr

I installed DDSCAT and prerequisites, but get the error "ddscat not found" when running the code for the RCTGLPRSM example. What is the reason for the error? Please help!

Error: bash - ddscat: command not found by Amey (guest), 02 Mar 2017 19:22
Sergey Ruzankin (guest) 16 Feb 2017 10:03
in discussion DDSCAT / General discussion » erythrocyte model

I have DDSCAT version with 3 models of erythrocyte (subrs tarery, tarery2, tarery3 with 1, 2 and 4 parameters). I can send you my modified version and can then improve this subrs for your purpose.

by Sergey Ruzankin (guest), 16 Feb 2017 10:03
draine (guest) 02 Feb 2017 20:12
in discussion DDSCAT / General discussion » examples like ANI_ELL_2 ELLIPSO_2 and SPHROID_2

These geometries are all supported by the DDSCAT code in the current distribution, and are fully documented in the Userguide.
Unfortunately, we have not provided "worked examples" for these three cases, but it should be straightforward for you to examine some of the "worked examples" in the distribution, and consult the UserGuide to understand how to modify the input file ddscat.par for the cases you are interested in.

by draine (guest), 02 Feb 2017 20:12

If you download examples (from ddscat.com) you can uncompress and untar the example file. There will be a directory "examples_exp" which has all the examples which we are currently providing. I.e. not all shapes have their corresponding example. If this is the case, you will need to change ddscat.par after the comment line ’ Target Geometry and Composition ’
to indicate which target shape you need. You can use CALLTARGET to examine various shapes (test shape generation) graphically. Each shape has its corresponding FORTRAN code which always begins with tar*, e.g. tarhex.f90. Sometimes it is convenient to look at these codes to see how the shape is created. You can also modify such code and create your own shape file (there are other ways of doing it as well).

Dear Sir,

I am research scholar in IIT Delhi, India. My research work is related to find the optical properties of the Nano-particles of different materials and different geometries. I found that the DDSCAT 7.3 is one of the most prominent code to study the characteristically properties of the different geometries. I am highly interested to find the optical properties for such geometries like ANI_ELL_2 ELLIPSO_2 and SPHROID_2. I have downloaded the user guide for DDSCAT 7.3 and its related examples from site of DDSCAT, But I did not found any example related to ANI_ELL_2, ELLIPSO_2 and SPHROID_2geometries.

Could you please provide the us these Examples (code) with their supporting files. The files will help me to study the optical properties of above geometries, which is very useful to enhance the efficiency of photovoltaics.

I will be highly obliged to your favor.

Thanking you

With Warm Regards

Shivani Bhardwaj

Dear Mr. Graber,

First: please use the latest release (7.3.2) from www.ddscat.org

The nearfield is the *total* "macroscopic" E field, including the
contribution of the incident wave. Section 29 of the UserGuide discusses
the distinction between microscopic and macroscopic E fields.
The nearfield is calculated on a grid throughout the user-specified
volume. Obviously, very large volumes imply very long computations
and memory requirements.

The scattering matrix S_ij describes the scattered field in the
"radiation zone" far from the target, where the scattered E field
falls off as 1/r .

Regarding Gaussian beams — if you know how the incident electric field
varies over the target volume, you can easily modify the subroutine
evale.f90 to generate the incident field at each lattice site in the
computational volume. I *think* that this would be the only required
change required to use "Gaussian beams".

Best,

Bruce T. Draine

Re: wxxxryyykzzz.En by pcirruspcirrus, 25 Jan 2017 23:13

On Wed, November 30, 2016 2:38 am, Joshua Graber wrote:
Hi Dr. Draine,

We have decided to use the Fortran version of DDSCAT, rather than the C++
version; yours is much more up to date, reliable, and developed (probably
because DDSCAT seems to be your idea and creation in the first place). We
are using it on a high-performance computer because of the processing
requirements.

The DDSCAT program is incredible; the development of it over the years is
proving very useful for people like us using it in independent research.

We are currently trying to use the program to model simple reflection and
refraction, where we convert the incident light as a Gaussian beam into
Electric field components to simulate a plane wave, then convert the
output E-field back into a wave. We are trying to make our own code to generate
visualization graphics; and we believe that this method will allow us to
use DDSCAT for twisted light rather than regular plane waves.

I was hoping you could speak a little to the meaning of the outputs: I do
believe that the wxxxryyykzzz.En binary output is the one we want to use
for our calculations. Are you defining the near field as such because it is
the sum of the incident field and the scattered field? I am a little bit
confused on this; most things discussing near-field and far-field
radiation seem to indicate that there may be some other important difference between
the two fields.

So… I am hoping to clarify that E_sca is indeed the E field that we will
be able to process in order to create our scattered light waveforms. If you
can clarify this for me, that would be awesome. Otherwise, I'm sure with
the help of our professor my group will be able to figure out a solution.
Thank you very much for your time.

Best,
Josh Graber

wxxxryyykzzz.En by pcirruspcirrus, 25 Jan 2017 23:13

Dear Josh,

Thanks for catching this bug — you can see that we haven't used 7.3.2 for
nearfield calculations…

I'll upload a new distribution of the 7.3.2
source to www.ddscat.org shortly.

Best,
—Bruce

Re: ddpostprocess problem by pcirruspcirrus, 25 Jan 2017 23:09

Nevermind; we found the problem. In the readnf subroutine there is an if
statement ensuring the correct version is used. This statement includes
7.3.0 and 7.3.1 but not 7.3.2, so it was just one small bug but I thought
you'd like to know about it. Everything works great once that line is
changed.

-Josh

Re: ddpostprocess problem by pcirruspcirrus, 25 Jan 2017 23:09

Dear Dr. Draine,

We have the latest release of ddscat up and running on the high
performance computing center here; however we need the ASCII files as
ddpostprocess.out is said to contain.

The ddposprocess.out file doesn't show up though, and the ddscat.log
file says
"file = w000r000k000.E1
file is incompatible with present version of subroutine SUBREADNF"

We think that might be our problem. Could you possibly speak to that? I
don't know if it's something wrong with the way it was set up on our
system of if there is some new update or an error in the subroutine, but
anything you could give us would help a lot.

Thanks,
Josh Graber

ddpostprocess problem by pcirruspcirrus, 25 Jan 2017 23:08
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