"KAPPA" example - How did we arrive at dT?

In the Lammps example on how to calculate thermal conductivity, Example 2 of the ReadMe file goes like this

Any number of things could have changed in the code in the ~2 years since

that README was written. These are small problems, run quickly, for demo

purposes. The difference between 0.71 and 0.78 is not significant.

If I run it today, I get the same answer as you.