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Calculation of Diffraction Elastic Constants

What is ISODEC?

ISODEC is a program for the calculation of diffraction elastic constants (DEC). DEC are used to convert lattice strain measured by diffraction into macroscopic stress. It can also calculate stress from measured d-spacings and vice versa. In the case of materials with preferred orientation it reads the crystallite orientation distribution function (ODF – must be supplied by the user) in textual form as output from free texture software (popla and MTEX). Program functions that use the ODF are: pole figure calculation, intensity fractions of overlapped reflections, and DEC (stress factors).

What does the installation package include?

The installation is very basic. Unzip the file in a directory of your choice and run IsoDEC.exe from there. The file pfcryst.dat contains single crystal elastic constants of some common materials and it should be in the same directory as IsoDEC. There is a basic help file (IsoDEC.pdf) and several examples consisting mainly of ODFs that were generated by popla (extension *.SHD, *.SOD or *.COD) or by MTEX (extension *.txt).

Will the source code be made available? 

Maybe later. ISODEC was written in Pascal/Delphi, and there is a good chunk of code in IsoDEC that was written using Numerical Recipes in Pascal by W. Press et al. So there are copyright issues and it cannot be simply made available until those code sections are replaced by public domain code. Also, the code is not very well documented.

Who maintains IsoDEC?

That would be me (Thomas Gnäupel-Herold: tg-h [at] (tg-h[at]nist[dot]gov)). All questions, and especially inconsistencies or bugs that are discovered using IsoDEC should be directed to me. As I am using it quite often I am naturally very interested in finding out about problems with IsoDEC. Suggestions about missing features are also welcome.

Created August 1, 2019, Updated June 2, 2021