In this chapter we introduce the fundamental concepts behind the Green Function Theory. We start from a description of the second quantization method and then, after introducing the ensemble average of an operator, we define the main object of the theory, the Green function. Further on, after obtaining the equation of motion for the Green function, we introduce the self-energy operator and we d...

In a relativistic Brueckner-Hartree-Fock calculation we include explicit negative-energy states in the two-body propagator. This is achieved by using the Gross spectator-equation, modified by medium effects. Qualitatively our results compare well with other RBHF calculations. In some details significant differences occur, e.g, our equation of state is stiffer and the momentum dependence of the ...

The multiconfiguration Dirac-Hartree-Fock (MCDHF) model has been employed to calculate the transition rates between the nine lowest levels of radium. The dominant rates were then used to evaluate the radiative lifetimes. The decay of the metastable 7s7p 3P0 state through 2-photon E1M1 and hyperfine induced channels is also studied.

The lattice Schwinger model with SLAC fermions is analyzed with two methods: a Hartree-Fock calculation of the ground state wavefunction, and a weak coupling approximation involving a truncated SLAC derivative. It is shown that $ Goldstone boson of chiral symmetry is actually present, but in the weak coupling limit it acquires infinite velocity. Submitted to Nuclear Physics B * Work supported b...

We determine the structure of neutron stars within a Brueckner-Hartree-Fock approach based on realistic nucleon-nucleon, nucleon-hyperon, and hyperon-hyperon interactions. Our results indicate rather low maximum masses below 1.4 solar masses. This feature is insensitive to the nucleonic part of the EOS due to a strong compensation mechanism caused by the appearance of hyperons and represents th...

An effective Hartree-Fock-Bogoliubov-type interaction is calculated for the Hubbard model in second order in the coupling by means of flow equations. A stability analysis is performed in order to obtain the transition into various possible phases. We find, that the second order contribution weakens the tendency for the antiferromagnetic transition. Apart from a possible antiferromagnetic transi...

We present the theory of analytical Hartree-Fock gradients for periodic systems as implemented in the code CRYSTAL. We demonstrate how derivatives of the integrals can be computed with the McMurchie-Davidson algorithm. Highly accurate gradients with respect to nuclear coordinates are obtained for systems periodic in 0,1,2 or 3 dimensions.

Bulk and single-particle properties of hot hyperonic matter are studied within the Brueckner-Hartree-Fock approximation extended to finite temperature. The bare interaction in the nucleon sector is the Argonne V18 potential supplemented with an effective three-body force to reproduce the saturating properties of nuclear matter. The modern Nijmegen NSC97e potential is employed for the hyperon-nu...

Beating of monopole modes in nuclear dynamics. Abstract Time-dependent Hartree-Fock simulations of the evolution of excited gold fragments have been performed. The observed dynamics appears more complex than the collective expansion picture. The minimum density is often not reached during the first density oscillation because of the beating of several collective compression modes.

Fission-related phenomena of heavy Λ hypernuclei are discussed with the constraint Skyrme-Hartree-Fock+BCS (SHF+BCS) method, in which a similar Skyrme-type interaction is employed also for the interaction between a Λ particle and a nucleon. Assuming that the Λ particle adiabatically follows the fission motion, we discuss the fission barrier height of 239 ΛU. We find that the fission barrier hei...