Essentials of Computational Chemistry, 2nd Edition

Book Preface

Since publication of the first edition I have become increasingly, painfully aware of just how short the half-life of certain ‘Essentials’ can be in a field growing as quickly as is computational chemistry. While I utterly disavow any hubris on my part and indeed blithely assign all blame for this text’s title to my editor, that does not detract from my satisfaction at having brought the text up from the ancient history of 2001 to the present of 2004. Hopefully, readers too will be satisfied with what’s new and improved.

So, what is new and improved? In a nutshell, new material includes discussion of docking, principal components analysis, force field validation in dynamics simulations, first-order perturbation theory for relativistic effects, tight-binding density functional theory, electronegativity equalization charge models, standard-state equilibrium constants, computation of pKa values and redox potentials, molecular dynamics with implicit solvent, and direct dynamics. With respect to improved material, the menagerie of modern force fields has been restocked to account for the latest in new and ongoing developments and a new menagerie of density functionals has been assembled to help the computational innocent navigate the forest of acronyms (in this last regard, the acronym glossary of Appendix A has also been expanded with an additional 64 entries). In addition, newly developed basis sets for electronic structure calculations are discussed, as are methods to scale various theories to infinite-basis-set limits, and new thermochemical methods. The performances of various more recent methods for the prediction of nuclear magnetic resonance chemical shifts are summarized, and discussion of the generation of condensed-phase potentials of mean force from simulation is expanded.

As developments in semiempirical molecular orbital theory, density functional theory, and continuum solvation models have proceeded at a particularly breakneck pace over the last three years, Chapters 5, 8, and 11 have been substantially reworked and contain much fresh material. In addition, I have tried wherever possible to update discussions and, while so doing, to add the most modern references available so as to improve the text’s connection with the primary literature. This effort poses something of a challenge, as I definitely do not want to cross the line from writing a text to writing instead an outrageously lengthy review article – I leave it to the reader to assess my success in that regard. Lastly, the few remaining errors, typographical and otherwise, left over from the second printing of the first edition have been corrected – I accept full responsibility for all of them (with particular apologies to any descendants of Leopold Kronecker) and I thank those readers who called some of them to my attention.

As for important things that have not changed, with the exception of Chapter 10 I have chosen to continue to use all of the existing case studies. I consider them still to be sufficiently illustrative of modern application that they remain useful as a basis for thought/discussion, and instructors will inevitably have their own particular favorites that they may discuss ‘offtext’ in any case. The thorough nature of the index has also, hopefully, not changed, nor I hope the deliberate and careful explanation of all equations, tables, and figures.

Finally, in spite of the somewhat greater corpulence of the second edition compared to the first, I have done my best to maintain the text’s liveliness – at least to the extent that a scientific tome can be said to possess that quality. After all, to what end science without humor?

Christopher J. Cramer
July 2004