Doctor of Philosophy (Ph.D.)
Electronic structure calculations using simulation cells for extended systems typically incorporate periodic boundary conditions as an attempt to mimic the real system with a practically infinite number of particles. Periodic boundary conditions introduce unphysical constraints that give rise to finite-size errors. In mean-field type calculations, the infinite size limit is achieved by simple quadrature in the Brillouin zone using a finite number of k-points. Many-body electronic structure calculations with explicit two-particle interactions cannot avail themselves of this simplification. Direct extrapolation is computationally costly while size correction with less accurate methods is frequently not sufficiently accurate. The Hartree-Fock method neglects the correlation energy, while the conventional density functional theory (DFT) uses the infinite-size limit of the exchange correlation function. Here we present a new finite-size exchange correlation function designed to be used in OFT calculations to give more accurate estimates of the finite-size errors. Applications of the method are presented, including the P2 molecule, fcc silicon, bcc sodium and BiScO3 perovskite. The method is shown to deliver rapidly convergent size-corrections.
© The Author
Kwee, Hendra, "Correction of finite size errors in many-body electronic structure calculations" (2008). Dissertations, Theses, and Masters Projects. Paper 1539623524.