Editing Theoretical chemistry (section)

== Closely related disciplines ==

Historically, the major field of application of theoretical chemistry has been in the following fields of research:
*[[Atomic physics]]: The discipline dealing with electrons and atomic nuclei.
*[[Molecular physics]]: The discipline of the electrons surrounding the molecular nuclei and of movement of the nuclei.  This term usually refers to the study of molecules made of a few atoms in the gas phase. But some consider that molecular physics is also the study of bulk properties of chemicals in terms of molecules.
*[[Physical chemistry]] and [[chemical physics]]: Chemistry investigated via physical methods like [[laser]] techniques, [[scanning tunneling microscope]], etc. The formal distinction between both fields is that physical chemistry is a branch of chemistry while chemical physics is a branch of physics.  In practice this distinction is quite vague. 
*[[Many-body theory]]: The discipline studying the effects which appear in systems with large number of constituents. It is based on [[quantum physics]] – mostly [[second quantization]] formalism – and [[quantum electrodynamics]].

Hence, theoretical chemistry has emerged as a branch of research.  With the rise of the [[density functional theory]] and other methods like [[molecular mechanics]], the range of application has been extended to chemical systems which are relevant to other fields of chemistry and physics, including [[biochemistry]], [[condensed matter physics]], [[nanotechnology]] or [[molecular biology]].