PT Unknown AU Schoof, T TI Configuration Path Integral Monte Carlo :ab initio simulations of fermions in the warm dense matter regime PY 2017 PU Christian-Albrechts-Universität zu Kiel WP https://macau.uni-kiel.de/receive/diss_mods_00020964 LA en DE quantum Monte Carlo path integral; fermions; warm dense matter; finite temperatures; homogeneous electron gas; harmonic oscillator; Matsubara Green function; Quanten-Monte-Carlo; Pfadintegral; Fermionen; warme dichte Materie; endliche Temperaturen; homogenes Elektronengas; harmonischer Oszillator; Matsubara-Green-Funktion AB Recent advances in warm dense matter physics, e.g. laser compressed matter, lead to an increasing interest in the description of correlated, degenerate electrons at finite temperatures. Path integral Monte Carlo (PIMC) methods cannot correctly describe weakly to moderately coupled and strongly degenerate Fermi systems due to the so-called fermion sign problem. The Configuration Path Integral Monte Carlo (CPIMC) approach greatly reduces the sign problem and allows for the exact computation of thermodynamic properties in this regime. In addition, the first successful implementation of the diagrammatic worm algorithm for a general Hamiltonian in Fock space with arbitrary pair interactions gives direct access to the Matsubara Green function. This thesis demonstrates the capabilities of the CPIMC approach for a model system of Coulomb interacting fermions in a two-dimensional harmonic trap. The correctness of the CPIMC implementation is verified by rigorous comparisons with an exact diagonalization method. Benchmark results are presented, which reveal large errors of the Hartree-Fock approximation in open shell configurations even for weak coupling and a significant deviation of multi-level blocking PIMC data in the complete basis set limit. The application of the CPIMC method to the warm dense homogeneous electron gas (HEG) quantifies the accuracy of recently published restricted PIMC (RPIMC) results, which have been the basis for the construction of exchange-correlation free energy functionals to be used in finite-temperature density functional theory calculations of warm dense matter. It is shown that the errors of the RPIMC data exceed 10 % at intermediate densities. Additionally, highly accurate data for the exchange-correlation energy at high densities, which are inaccessible by the RPIMC method, are provided. These results are needed to significantly increase the quality of future exchange-correlation functionals to be used in finite-temperature applications. PI Kiel ER