To understand molecular devices, we

To understand molecular devices, we must first understand quantum chemistry. What is quantum chemistry? Quantum chemistry is not a single discipline, but a new discipline formed by the integration of modern natural science disciplines. It studies the microstructure of molecules, the microstructure of solids and the property relationship of these structures. The same research is based on the principle of quantum mechanics. It can be said that quantum chemistry belongs to theoretical chemistry and occupies a large proportion in it. Theoretical chemistry presents results macroscopically, while quantum chemistry is microcosmic, which pays more attention to details, explains some life rules found in daily life more clearly, and does not blindly explain it, but analyzes it gradually and hierarchically. Cohen and Popper, winners of the Nobel Prize in Chemistry in 1998, won the Nobel Prize in Chemistry that year because they made outstanding contributions in the field of quantum chemistry by means of density functional theory (DFI) and calculation methods.