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Computational chemistry has long been at the forefront of
simulation technology and scientific computing in general.
From studying the energetics of a hydrogen molecule to
developing new materials for aircraft design, computational
chemistry has established itself as an indispensible piece
of the world's research efforts. In this installment, we'll
examine the basic methods of computational chemistry and
briefly discuss the kinds of problems for which each is
best suited.
Quantum Mechanics
Quantum chemistry problems are approached from one of two standpoints: ab initio or semiempirical. In an ab initio calculation, the mathematical formalism needed to describe a problem is retained in full, and no experimental data is figured into the calculation. In other words, there are no funny shortcuts introduced in the formulation of the problem, although some "tricks" may be used to arrive at an answer. A semiempirical approach, however, employs a less-stringent mathematical model and may make use of experimental data to offset some of the computational intricacies. Whether ab initio or semiempirical, quantum methods are used to explore interactions among particles, learn more about the properties of an atom or molecule, help define reaction pathways, and for many other important issues pertaining to the small-scale chemical problem (small-scale being one to maybe 100 atoms total). Classical Mechanics Classical mechanics, as the name implies, uses the so-called classical, usually Newtonian, equations of motion to study systems of particles. In this case, because we are not starting from first-principles, it is necessary to supply some information about how the particles in a system interact. This is most typically done with a semi-empirical force field. A semi-empirical force field is a mathematical construct which desribes how one chemical species interacts with any other chemical species it might encounter. These pairwise interactions are parameterized based on experimental data and quantum mechanical calculations. The great advantage to employing classical over quantum methods is that the calculations involved in the former are much less complicated than those necessary for the latter. As a consequence, much larger computational problems, in terms of the number of atoms involved, can be "solved" much more Go To Page: 1 2
The copyright of the article Computational Chemistry - Electrons to Airplanes in Scientific Computing is owned by . Permission to republish Computational Chemistry - Electrons to Airplanes in print or online must be granted by the author in writing.
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