> The research paper will tell you everything except how to reproduce this work in minimal effort, it's like they are hiding something.

They are. I used to work in an adjacent field. Everyone was open about doing it - they're competing with others for grants, and worry that if they reveal the secret sauce, others will move faster than they can.

You can say you performed a DFT calculation to get the result, but anyone who's studied these types of simulations/calculations knows that it's highly nontrivial to implement, with lots of coding and numerical tricks involved. So it's extremely hard to reproduce if you don't have detailed access to the algorithms.