Ab Initio Calculations

Ab Initio Calculations Synopsis

The book entitled Ab initio Calculations: Methods and Applications provides an overview of the most used ab initio quantum methods and their applications in different fields. Ab initio calculations offer results and details that are not obtainable from experimental data and a degree of assurance which is not accessible with the empirical methods. The methods Hartree–Fock, Moller–Plesset Perturbation theory and Coupled Cluster theory are discussed. Both their accuracy and computational performance are summarized in the first part of the book. The rest of the book is emphasizing on the significant advances in the implementation of the ab initio methods in the last years. Biological applications of the ab initio methods, subject to part 2 of the book, are mainly focused on the modelling of enzymatic catalysis and active-site chemistry. Here are also shown interesting investigations of other phenomena, such as tautomerism, occurring in nucleic acid bases and important for the stability of DNA, considering that tautomerism partially explains the structure of nucleic acids and their mutations. Another interesting phenomenon as molecular photostability happening in nitrogen containing heterocycles, DNA bases and base pairs is briefly described. In the last years, materials-science applications are fast developed and currently involve examination of highly complex structures. Both bulk and surface properties can be calculated for solids as the results are in excellent agreement with experimental data. Here a special attention is given to the investigation of materials with optical properties and of nanocrystals for potential use as electronic devices. The interest to the application of the ab initio methods to nanotechnology is quite recent and corresponds to the increasing applicability of these materials in various types of devices. The systems that have been considered in this book are carbon nanostructures as graphene, buckyballs and nanotubes. In particular, the special effect of the quantum-restricted size and structural modification on both chemical and electrical properties are investigated. The continuous theoretical developments and the decrease in the cost/performance of computing guarantee the fast progress of the ab initio calculations in the next years, advancing toward the goal of achieving a complete agreement with the experiments.

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