l is  ψ  (  ε  ,  D  k  ,  R  k  )  =  0  0  ε  :  𝔼  (  𝔼  0  ,  D  k  )  :  ε  \+  0  0  ∑  k  =  0  0  K  k  R  k  0  ,  which leads to the following expressions for the conjugate thermodynamic associated variables  σ  =  