Relativistic Quantum Theory of Atoms and Molecules

The theory underlying the widely used GRASP relativistic atomic structure program, the DARC electron-atom scattering code and the new BERTHA relativistic molecular structure program is presented in depth, together with computational aspects relevant to practical calculations. This book presents a unified approach to modern relativistic theory of the electronic structure of atoms and molecules which will provide experimental and theoretical scientists and graduate students with a range of powerful computational tools for a growing range of physical, chemical, technological and biochemical applications. Starting from its foundations in quantum electrodynamics, the book contains a careful account of relativistic atomic and molecular structure based on Dirac's relativistic Hamiltonian, and the numerical algorithms implemented by modern computer programs. The relativistic atomic structure code GRASP, which can compute atomic energy levels, radiative transition rates and other atomic properties using the multiconfigurational Dirac-Hartree-Fock or relativistic configuration interaction methods, is reviewed along with the relativistic R-matrix code DARC, which is used for the high precision modelling of the interactions of atoms and ions with photons and electrons. The recently developed BERTHA relativistic molecular structure code, the first to exploit fully the symmetry properties of Dirac 4-component spinors, provides a new resource for studying the properties of molecules, atomic clusters and other materials, especially those containing heavy elements for which a relativistic model is essential. Relativistic quantum electrodynamics, which describes the electromagneticinteractions of electrons and atomic nuclei, provides the basis for modeling the electronic structure of atoms, molecules and solids and of their interactions with photons and other projectiles. The theory underlying the widely used GRASP relativistic atomic structure program, the DARC electron-atom scattering code and the new BERTHA relativistic molecular structure program is presented in depth, together with computational aspects relevant to practical calculations. Along with an understanding of the physics and mathematics, the reader will gain some idea of how to use these programs to predict energy levels, ionization energies, electron affinities, transition probabilities, hyperfine effects and other properties of atoms and molecules.