Hi dear, i make some post about these code, because I’m literally going crazy.
The problem is relative to the SS, I thought I introduced the steady state correctly by referring to the paper, but that’s not the case, can anyone tell me why? many thanks in advance.

You declare your model to be (log)-linear but there clearly are some equations that are not linear such as eq. 6 and 10. Basically all equations where dynare gives you NaN’s in the residuals. If the model is correctly log-linearized, all endogenous variables have zero steady state.

There should not be a rkss in the marginal cost equation. As @DoubleBass wrote, check your linearization. Removing the constant yields a 0 steady state: simulazione2_e.mod (2.5 KB)

Dear professor, thank you very much for your precious help, I would like to ask you what the predetermined_variables k function is for. Furthermore, I noticed that the impulse responses come out a little different compared to the original paper, can you tell me why?
Thank you again for your precious help.

Dynare has a stock at the end of period timing convention, while you used a stock at the beginning of period convention for capital. The predetermined_variables command tells Dynare about this difference in timing.

Regarding replication results, the standard answer is