The many-body-theoretical basis and applications of theoretical
spectroscopy of condensed matter, e.g. crystals, nanosystems, and
molecules are unified in one advanced text for readers from graduate
students to active researchers in the field. The theory is developed
from first principles including fully the electron-electron interaction
and spin interactions. It is based on the many-body perturbation theory,
a quantum-field-theoretical description, and Green's functions. The
important expressions for ground states as well as electronic
single-particle and pair excitations are explained. Based on
single-particle and two-particle Green's functions, the Dyson and
Bethe-Salpeter equations are derived. They are applied to calculate
spectral and response functions. Important spectra are those which can
be measured using photoemission/inverse photoemission, optical
spectroscopy, and electron energy loss/inelastic X-ray spectroscopy.
Important approximations are derived and discussed in the light of
selected computational and experimental results. Some numerical
implementations available in well-known computer codes are critically
discussed. The book is divided into four parts: (i) In the first part
the many-electron systems are described in the framework of the
quantum-field theory. The electron spin and the spin-orbit interaction
are taken into account. Sum rules are derived. (ii) The second part is
mainly related to the ground state of electronic systems. The total
energy is treated within the density functional theory. The most
important approximations for exchange and correlation are delighted.
(iii) The third part is essentially devoted to the description of
charged electronic excitations such as electrons and holes. Central
approximations as Hedin's GW and the T-matrix approximation are
discussed.(iv) The fourth part is focused on response functions measured
in optical and loss spectroscopies and neutral pair or collective
excitations.
