Theoretical Chemistry refers to using mathematical methods to express chemistry problems. And computational chemistry “is a branch of chemistry that uses computer simulation to assist in solving chemical problems. It uses methods of theoretical chemistry, incorporated into efficient computer programs, to calculate the structures and properties of molecules and solids.” (Wiki) Computational chemistry does not pursue perfection or flawlessness because only a few chemical systems can be accurately calculated. However, almost all types of chemical problems can be and has been used approximation algorithms to express.
Theoretically, we can utilize fairly accurate theoretical method
to calculate any molecules. Many computing software have contain these precise
methods. But the amount calculating of these methods will increase exponentially
or with the increasing number of electrons. Thus, they can only be applied to
small molecules. For larger systems, it often adopts other larger degree approximation
methods to find a balance between the accuracy results and the amount of
computing.
Computational chemistry mainly uses existing computer
programs and methods to study specific chemical problems. The development of algorithms
and computer programs is completed by theoretical chemists and theoretical
physicists. When studying properties of atomic and molecular, chemical reaction
pathways, and other issues, it often focuses on solving two problems:
2. Using a computer program to do molecular dynamics
simulations. This tries to compound predicted starting conditions of
experiments, study chemical reaction mechanism, and explain the reaction
phenomena, etc.
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