J integral calculation in in.eshelby_static example of ATC package Lammps

Dear Lammps users,
I am using the ATC package of LAMMPS and at the moment I am working on the in.eshelby_static example. This test calculates the J-integral for a sequence of different loads for a system with a crack tip. In the example, concentric loops around one/both of the crack tips are made and boundary_integral of eshelby stress tensor is calculated and stored in the GLOBALS file. I can see that a second-order tensor is stored for each increment of loading performed in the GLOBALS file, but I have difficulty understanding how the J-integral value is computed from this tensor.
I really appreciate your help regarding this matter.
Melika Vokhshoori

You need to either infer it from the source code or contact the AtC developers (who unfortunately have moved on to other projects and thus may not be responsive. AtC has not seen active development since 2014).