What Is Computational Chemistry?

Over the past month or so, many of my family and friends have asked me about what I will be doing in grad school, and what I can do with it after I'm done.  I've decided to use this post to explain, to the best of my abilities, just what computational chemistry is in layman's terms.

So first, what is computational chemistry?

--Computational chemistry is a branch of chemistry that uses computers to help predict the behavior of chemical systems.  Computational chemists use the principles of math, physics, chemistry, and computing to solve very complex problems.

Most of the time, when doing computational chemistry, we are given a chemical system (see definition below) and we wish to either predict a chemical reaction that will take place or predict the shape, or geometry, the particles in our system will most likely form.  In other words, we are mainly concerned with the interactions that take place between particles.  When I say particles I mean electrons, protons, neutrons, atoms, molecules, and macromolecules.

There are two parts to a chemical system:
1) What is in the system?  I need to tell the computer what type of particles are going to interact.
2) Where are the particles and how are they moving around?  I need to tell the computer how far the particles are from each other, and I also have to provide velocities for each particle.

The goal of my research will be to design and test computer models of chemical systems.  I will be designing models based on initial conditions of a chemical system and will modify the program until my predictions match experimental results within a given range.  Then, once I know a model works for one type of system, I can use the model to predict behavior of systems very similar to the initial one.

If you have any other specific questions, feel free to ask.  I hope this answers at least some of the questions people had.