Theoretical chemistry involves the use of physics to explain or predict chemical phenomena. In recent years, it has consisted primarily of quantum chemistry, i.e., the application of quantum mechanics to problems in chemistry. Theoretical chemistry may be broadly divided into electronic structure, dynamics, and statistical mechanics. In the process of solving the problem of predicting chemical reactivities, these may all be invoked to various degrees. Other "miscellaneous" research areas in theoretical chemistry include the mathematical characterization of bulk chemistry in various phases (e.g. the study of chemical kinetics) and the study of the applicability of more recent math developments to the basic areas of study (e.g. for instance the possible application of principles of topology to the study of electronic structure.) The latter area of theoretical chemistry is sometimes referred to as mathematical chemistry. Chemistry - the study of interactions of chemical substances with one another and energy based on the structure of atoms, molecules and other kinds of aggregrates Chemistry (from Egyptian kēme (chem), meaning earth[1]) is the science concerned with the composition, structure, and properties of matter, as well as the... Quantum chemistry is a branch of theoretical chemistry, which applies quantum mechanics and quantum field theory to address issues and problems in chemistry. ... Fig. ... Reactivity refers to the rate at which a chemical substance tends to undergo a chemical reaction in time. ... In physical chemistry, chemical kinetics or reaction kinetics study reaction rates in a chemical reaction. ... Mathematical chemistry is a branch of theoretical chemistry. ...

Much of this may be categorized as computational chemistry, although computational chemistry usually refers to the application of theoretical chemistry in an applied setting, usually with some approximation scheme such as certain types of post Hartree-Fock, Density Functional Theory, semiempirical methods (like for instance PM3) or force field methods. Some chemical theorists apply statistical mechanics to provide a bridge between the microscopic phenomena of the quantum world and the macroscopic bulk properties of systems. Computational chemistry is a branch of chemistry that uses the results of theoretical chemistry incorporated into efficient computer programs to calculate the structures and properties of molecules and solids, applying these programs to complement the information obtained by actual chemical experiments, predict hitherto unobserved chemical phenomena, and solve related problems. ... In computational chemistry, Post-Hartree-Fock methods are the set of methods developed to improve on the Hartree-Fock (HF), or self-consistent field (SCF) method. ... Density functional theory (DFT) is a quantum mechanical method used in physics and chemistry to investigate the electronic structure of many-body systems, in particular molecules and the condensed phases. ... Computational chemistry is a branch of chemistry that uses the results of theoretical chemistry incorporated into efficient computer programs to calculate the structures and properties of molecules and solids, applying these programs to complement the information obtained by actual chemical experiments, predict hitherto unobserved chemical phenomena, and solve related problems. ... PM3, or Parameterized Model number 3, is a semi-empirical method for the quantum calculation of molecular electronic structure in computational chemistry. ... A force field is used to minimize the bond stretching energy of this ethane molecule. ... Statistical mechanics is the application of probability theory, which includes mathematical tools for dealing with large populations, to the field of mechanics, which is concerned with the motion of particles or objects when subjected to a force. ...

Theoretical attacks on chemical problems go back to the earliest days, but until the formulation of the Schrödinger equation by the Austrian physicist Erwin Schrödinger, the techniques available were rather crude and speculative. Currently, much more sophisticated theoretical approaches, based on Quantum Field Theory and Nonequilibrium Green Function Theory are in vogue. For a non-technical introduction to the topic, please see Introduction to quantum mechanics. ... This article needs additional references or sources for verification. ... Bust of Schrödinger, in the courtyard arcade of the main building, University of Vienna, Austria. ... Quantum field theory (QFT) is the quantum theory of fields. ...

Branches of theoretical chemistry

Quantum chemistry

The application of quantum mechanics to chemistry

Computational chemistry

The application of computer codes to chemistry

Molecular modelling

Methods for modelling molecular structures without necessarily referring to quantum mechanics. Examples are molecular docking, protein-protein docking, drug design, combinatorial chemistry.

Molecular dynamics

Application of classical mechanics for simulating the movement of the nuclei of an assembly of atoms and molecules.

Molecular mechanics

Modelling of the intra- and inter-molecular interaction potential energy surfaces via a sum of interaction forces.

Mathematical chemistry

Discussion and prediction of the molecular structure using mathematical methods without necessarily referring to quantum mechanics.

Theoretical chemical kinetics

Theoretical study of the dynamical systems associated to reactive chemicals and their corresponding differential equations.

Quantum chemistry is a branch of theoretical chemistry, which applies quantum mechanics and quantum field theory to address issues and problems in chemistry. ... Fig. ... Computational chemistry is a branch of chemistry that uses the results of theoretical chemistry incorporated into efficient computer programs to calculate the structures and properties of molecules and solids, applying these programs to complement the information obtained by actual chemical experiments, predict hitherto unobserved chemical phenomena, and solve related problems. ... Source code (commonly just source or code) is any series of statements written in some human-readable computer programming language. ... The backbone dihedral angles are included in the molecular model of a protein. ... Computational molecular docking is a research technique for predicting whether one molecule will bind to another, usually a protein. ... Protein-protein docking is the determination of the molecular structure of complexes formed by two or more proteins without the need for experimental measurement. ... Drug design is the approach of finding drugs by design, based on their biological targets. ... Combinatorial chemistry involves the rapid synthesis and/or the computer simulation of a large number of different but structurally related molecules. ... Molecular dynamics (MD) is a form of computer simulation wherein atoms and molecules are allowed to interact for a period of time under known laws of physics, giving a view of the motion of the atoms. ... Classical mechanics is used for describing the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies. ... The term molecular mechanics refers to the use of Newtonian mechanics to model molecular systems. ... A potential energy surface is generally used within the adiabatic or Born–Oppenheimer approximation in quantum mechanics and statistical mechanics to model chemical reactions and interactions in simple chemical and physical systems. ... In physics, force is anything that can cause a massive body to accelerate. ... Mathematical chemistry is a branch of theoretical chemistry. ... In physical chemistry, chemical kinetics or reaction kinetics study reaction rates in a chemical reaction. ... The Lorenz attractor is an example of a non-linear dynamical system. ... A chemical substance is any material substance used in or obtained by a process in chemistry: A chemical compound is a substance consisting of two or more chemical elements that are chemically combined in fixed proportions. ... A simulation of airflow into a duct using the Navier-Stokes equations A differential equation is a mathematical equation for an unknown function of one or several variables which relates the values of the function itself and of its derivatives of various orders. ...

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, the theoretical chemistry discipline is sometimes seen as a branch of those fields of research. Nevertheless, more recently, 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 like biochemistry, condensed matter physics, nanotechnology or molecular biology. Atomic physics (or atom physics) is the field of physics that studies atoms as isolated systems comprised of electrons and an atomic nucleus. ... Molecular physics is the study of the physical properties of molecules and of the chemical bonds between atoms that bind them into molecules. ... Physical chemistry is the application of physics to macroscopic, microscopic, atomic and particulate phenomena in chemical systems[1]within the field of chemistry traditionally using the principles, practices and concepts of thermodynamics, quantum chemistry, statistical mechanics and kinetics. ... Chemical physics is a subdiscipline of physics that investigates physicochemical phenomena using techniques from atomic and molecular physics and condensed matter physics; it is the branch of physics that studies chemical processes from the point of view of physics. ... Experiment with a laser (US Military) In physics, a laser is a device that emits light through a specific mechanism for which the term laser is an acronym: Light Amplification by Stimulated Emission of Radiation. ... Image of substitutional Cr impurities (small bumps) in the Fe(001) surface. ... This article is about the many-body problem in quantum mechanics. ... Fig. ... Second quantization refers to quantizing fields by expressing them as operator-valued distributions The most elementary, or semiclassical treatments of quantum mechanics fix the number of particles and treat the field classically, including it as a parameter in the Hamiltonian or Lagrangian or whatever. ... Quantum electrodynamics (QED) is a relativistic quantum field theory of electrodynamics. ... Density functional theory (DFT) is a quantum mechanical method used in physics and chemistry to investigate the electronic structure of many-body systems, in particular molecules and the condensed phases. ... The term molecular mechanics refers to the use of Newtonian mechanics to model molecular systems. ... Biochemistry is the study of the chemical processes and transformations in living organisms. ... Condensed matter physics is the field of physics that deals with the macroscopic physical properties of matter. ... Buckminsterfullerene C60, also known as the buckyball, is the simplest of the carbon structures known as fullerenes. ... Molecular biology is the study of biology at a molecular level. ...

Bibliography

• Attila Szabo and Neil S. Ostlund, Modern Quantum Chemistry: Introduction to Advanced Electronic Structure Theory, Dover Publications; New Ed edition (1996) ISBN-10: 0486691861, ISBN-13: 978-0486691862

External links

• University of Cambridge, Centre for Computational Chemistry
• University of Groningen, Theoretical Chemistry Group
• University of Lund, Theoretical Chemistry Group
• Vrije Universiteit Amsterdam, Chemistry and Pharmaceutical Sciences
• VCCLAB: Virtual Computational Chemistry Laboratory
• NIST Computational Chemistry Comparison and Benchmark DataBase

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