Has anyone used the UMATHT subroutine in CalculiX before?

Hello,

I want to add the internal energy generated as a result of reaction kinetics to the system by using the u (internal energy) variable in the umatht subroutine, but it says “not used” for the u variable. I think I need to make some edits in CalculiX codes to use this variable as in Abaqus, how can I do that?

I will be grateful if you could help me.

Screenshot from 2022-05-12 15-25-00