Introduction to theoretical chemistry

In this chapter a revision of the methods that had to be studied during this thesis it is found. Some of them had to be modified or developed, some others only used as already implemented algorithms in program packages, and finally we also explain some methods that are not used at all. One may find this chapter a too long exposition of methods, or an unnecessary task since these are standard methods. However, during a research task the theoretical chemist must know the wide variety of methods available in the literature in order to proceed with his own work. Moreover, in my opinion the learning labor is one of the most important tasks during the initial formation of a scientist.

Even when using very standard techniques, theoretical chemistry is constantly progressing and sometimes there is not a clear separation between the chemist that develops or implements the tools (theoretical chemist) and the chemist that applies standard techniques to solve relevant chemical problems (computational chemist).

The first section contains a general but likely particular overview of techniques and strategies in theoretical chemistry. In the second, third, fourth and fifth section a deeper explanation of the methods used in this thesis is given. Since most of these methods are well known there will not be a full coverage of these fields. A lot of good books and articles already exist and the original references may be found in there. In particular, for the Quantum Chemistry section I prefer the Pauling's[8], Pilar's[9] and Daudel's[10] books for its fundamental exposition of the problem, and the Jensen's [11] book for a very complete and updated review.

For the optimization section in my opinion there is no book covering all the wide range of methods very deeply. They may be found in Fletcher's [12], Leach's [13] and Schlick's [14] book. In the molecular dynamics and statistical simulation section, the Leach's[13] covers a recent overview of standard techniques and while Allen-Tildesley's [15] covers the basis of simulation techniques, McQuarrie's [16] stands for a deeper conceptual and fundamental background on the whole field.