ECP Pattern Simulations

ECP Pattern Simulations

Once you have a complete ECP master pattern simulation, the next step is to set up your detector parameters and grain orientations to compute actual patterns. For this help page, we will assume that you already know the relevant parameters, and you simply want to compute the patterns.

The relevant program is called EMECP, and you generate the name list file template by typing:

EMECP -t

This generates a namelist template file which you need to rename to something like EMECP.nml. The content of this file is as follows:

 &ECPlist
! The line above must not be changed
!
! The values below are the default values for this program
!
! crystal structure filename
 xtalname = 'undefined',
! size of output pattern in pixels (image is always square npix x npix)
 npix = 256,
! half angle of cone for incident beams (degrees)
 thetac = 5.0,
! mask pattern or not; 'y' or 'n'
 maskpattern = 'n',
! monte carlo input file; path relative to EMdatapathname
 energyfile = 'undefined',
! master pattern input file; path relative to EMdatapathname
 masterfile = 'undefined',
! input file for list of angles
 anglefile = 'undefined',
! euler angle convention in input angle file; 'hkl' or 'tsl'
 eulerconvention = 'hkl',
! gamma scaling value
 gammavalue = 1.0,
! output format; 'gui' for IDL and 'bin' for dictionary
 outputformat = 'gui',
! output file ; path relative to EMdatapathname
 datafile = 'undefined',
! number of threads for parallel execution
 nthreads = 1,
! tilt of the sample; only one angle incorporated for now
 sampletilt = 0.D0,
! detector geometry parameters
! working distance [in mm]
 workingdistance = 13.0,
! inner radius of annular detector [in mm]
 Rin = 2.0,
! outer radius of annular detector [in mm]
 Rout = 6.0,
!
!==============================================================
! the nml parameters below are only used in case of two layered structure;
! ignore them all for normal ECP calculation
!==============================================================
! foil normal of film
 fn_f = 0,0,1,
! foil normal of substrate
 fn_s = 0,0,1,
! second (substrate) crystal structure filename
 xtalname2 = 'undefined',
! plane normal in Film
 gF = 0,0,0,
! plane normal in Substrate
 gS = 0,0,0,
! direction in Film
 tF = 0,0,0,
! direction in Substrate
 tS = 0,0,0,
! smallest d-spacing to take into account [nm]
 dmin = 0.025,
! film thickness if present  (0.0 if not present)
 filmthickness = 0.0,
! output file for film signal
 filmfile = 'undefined',
! output file for substrate signal
 subsfile = 'undefined'
 /

For most of the parameters above, the one-liner explaining things should be sufficient. This program is scheduled to be updated with additional options in the next version of EMsoft. The outputformat parameter should always be set to bin to generate an HDF5 output file.

Example ECPs for Ni using some random orientations are shown below: