Scientific Computing: Computational Chemistry

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:

1. Using computer programs with quantum chemistry equations to calculate the properties of material such as energy, dipole moment, vibration frequencies and so on.  It can explain some specific chemical 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.

Reference:

http://en.wikipedia.org/wiki/Computational_chemistry