meet a problem? asking for help!

Mon, 02 Jan 2017 20:25:04 +0000

FATAL ERROR IN PROCEDURE: ZBCG2WP
ITERN>ITERMX
EXECUTION ABORTED

How to solve this problem? Thanks a lot!

Using DDSCAT with MPI for nearfield calculations: fixed in DDSCAT 7.3.2

Thu, 25 Aug 2016 18:59:37 +0000

Sergey Ph. Ruzankin reported that DDSCAT 7.3.1 failed to properly carry out nearfield calculations (NRFLD=1 or 2) when used with MPI. Dr. Ruzankin also recommended some changes to DDSCAT.f90 to correct this problem.

The changes recommended by Dr. Ruzankin have now been implemented in a new release, DDSCAT 7.3.2, released today (2016 August 25) and available for download from ddscat.org — go to the "Downloads" tab. At this point in time we consider DDSCAT 7.3.2 to be fully compatible with MPI. If users encounter bugs with use under MPI, they should report them here.

Help with orientation issues

Thu, 30 Jun 2016 20:03:26 +0000

I have been working well with this program for awhile, but I hit snags every time I try to look at anything more complicated than a single sphere. I have tried both ellipsoids and cylinders, but I am never able to get my program to register the long edge of my shape. We have a software that converts the resulting extinction values as a function of wavelength into a number density as a function of diameter. But even when I rotate the ellipsoid at all angles, I am never able to see the number density peak signifying the long edge.

The best example I can give to help troubleshoot my issue is this ellipsoid (ddscat.par file copied at the bottom). I intended to create an ellipsoid with dimensions 7x7x11 nm and approximately 10,000 dipoles. I want the Qext values over a wavelength range of 200-1000 nm. I have tried this file for theta=0, theta=90, theta=0-90 (with 10 angles), as well as 0-90 for beta and theta, all while holding all the other angles constant at 0.. and every time I get the exact same Qext values. Shouldn't I get different extinction values when I am looking at the ellipsoid head on versus when it is rotated 90 degrees so I am looking at the long edge? Do you notice anything I am missing or doing wrong or do you have any suggestions of what I might try to change??

I've tried making this larger (70x70x110) and I've tried with as many as 100,000 dipoles as well, never with any success at recognizing the longer edge. I am using version 7.3.1, but not the most recent version of it.

Thank you!!

' ========== Parameter file for v7.3 ==================='
' Preliminaries '
'NOTORQ' = CMDTRQ*6 (DOTORQ, NOTORQ) — either do or skip torque calculations
'PBCGS2' = CMDSOL*6 (PBCGS2, PBCGST, GPBICG, QMRCCG, PETRKP) — CCG method
'GPFAFT' = CMETHD*6 (GPFAFT, FFTMKL) — FFT method
'GKDLDR' = CALPHA*6 (GKDLDR, LATTDR, FLTRCD) — DDA method
'NOTBIN' = CBINFLAG (NOTBIN, ORIBIN, ALLBIN) — binary output?
' Initial Memory Allocation '
100 100 100 = dimensioning allowance for target generation
' Target Geometry and Composition '
'ELLIPSOID' = CSHAPE*9 shape directive
25 25 39.286 = shape parameters 1 - 3
1 = NCOMP = number of dielectric materials
'../diel/polystyeq' = file with refractive index 1
' Additional Nearfield calculation? '
0 = NRFLD (=0 to skip nearfield calc., =1 to calculate nearfield E)
0.0 0.0 0.0 0.0 0.0 0.0 (fract. extens. of calc. vol. in -x,+x,-y,+y,-z,+z)
' Error Tolerance '
1.00e-5 = TOL = MAX ALLOWED (NORM OF |G>=AC|E>-ACA|X>)/(NORM OF AC|E>)
' Maximum number of iterations '
1000 = MXITER
' Integration limiter for PBC calculations '
1.00e-2 = GAMMA (1e-2 is normal, 3e-3 for greater accuracy)
' Angular resolution for calculation of , etc. '
0.5 = ETASCA (number of angles is proportional to [(3+x)/ETASCA]^2 )
' Wavelengths (micron) '
200 1000 801 'LIN' = wavelengths (1st,last,howmany,how=LIN,INV,LOG,TAB)
' Refractive index of ambient medium '
1.0000 = NAMBIENT
' Effective Radii (micron) '
4.0691 4.0691 1 'LIN' = eff. radii (1st,last,howmany,how=LIN,INV,LOG,TAB)
' Define Incident Polarizations '
(0,0) (1.,0.) (0.,0.) = Polarization state e01 (k along x axis)
2 = IORTH (=1 to do only pol. state e01; =2 to also do orth. pol. state)
' Specify which output files to write '
0 = IWRKSC (=0 to suppress, =1 to write ".sca" file for each target orient.
' Specify Target Rotations '
0. 0. 1 = BETAMI, BETAMX, NBETA (beta=rotation around a1)
0. 90. 10 = THETMI, THETMX, NTHETA (theta=angle between a1 and k)
0. 0. 1 = PHIMIN, PHIMAX, NPHI (phi=rotation angle of a1 around k)
' Specify first IWAV, IRAD, IORI (normally 0 0 0) '
0 0 0 = first IWAV, first IRAD, first IORI (0 0 0 to begin fresh)
' Select Elements of S_ij Matrix to Print '
9 = NSMELTS = number of elements of S_ij to print (not more than 9)
11 12 21 22 31 33 44 34 43 = indices ij of elements to print
' Specify Scattered Directions '
'LFRAME' = CMDFRM (LFRAME, TFRAME for Lab Frame or Target Frame)
1 = NPLANES = number of scattering planes
0. 0. 180. 1 = phi, theta_min, theta_max (deg) for plane A

Writing output with > 1000 orientations

Fri, 10 Jun 2016 17:55:34 +0000

DDSCAT 7.3 added support for writing output with > 1000 orientations. It works very well, but there is a vestigial check in the REAPAR function that disables much of this functionality.

In version 7.3.1's code (version 160601), in reapar.f90:
1470 ! check that user has not requested more than 1000 orientations and
1471 ! IWRKSC=1
1472
1473 IF(IWRKSC>0.AND.(NBETA*NTHETA*NPHI)>1000)THEN
1474 CALL ERRMSG('FATAL','REAPAR', &
1475 'error: if IWRKSC=1, NBETA*NTHETA*NPHI must be .le. 1000')
1476 ENDIF

Given the changes to the code in 7.3, this can be removed.

Report errors (new threads)

meet a problem? asking for help!

Using DDSCAT with MPI for nearfield calculations: fixed in DDSCAT 7.3.2

Help with orientation issues

Writing output with > 1000 orientations