(3.8.4) Chermette : Young researchers may be reminded of the difficult youth of DFT in chemistry, even though interesting results were obtained and interpreted in the 1970s and 1980s. A similar situation occurred in other domains, such as the quasi-crystal discovery, not accepted by the crystallographers for a while. 472 (3.8.5) Kronik : DFT interacts with the "real world" in three ways: