Explanation

The branch of chemistry that applies quantum mechanics to discuss the structure, properties and relationships of substances at the molecular level. It proposes a series of concepts such as orbitals, electron clouds, resonance, hybridization, etc., laying the theoretical foundation for the relationship between molecular structure and properties, and becoming one of the important theoretical foundations of modern chemistry. quantum chemistry can be divided into three parts: ① basic theory, the core of which is multi-body theory. The most important molecular problems dealt with by quantum mechanics are three kinds of chemical bond theories (valence bond theory, molecular orbital theory and coordination field theory); Secondly, there are density matrix theory, density functional theory, multi-body perturbation theory and collision theory dealing with dynamic problems. In recent years, there have been relativistic effects, correlation energy correction, and adiabatic approximation correction The calculation method is improved based on the principles of multi body theory to achieve practical purposes. Usually combined with computers, various universal standard programs are compiled. There are mainly ab initio calculation methods and various semi empirical autonomous field methods based on it. There are also methods for converting delocalized molecular orbitals into localized molecular orbitals Applied research, that is, quantum chemistry is used to calculate the structures, properties and interrelationships of various molecules and solids (including stable and unstable, ground state and excited state), as well as the interactions and chemical reactions between molecules. The results include: the structure and chemical bond properties of new molecules, molecular excited states and spectral problems, quantum theory of chemical reaction and photochemistry, solid surface structure and catalytic mechanism, biochemistry and pharmaceutical chemistry, and quantum chemical research of materials.

Classification