The electronic Fermi surface is an object of fundamental interest in many sub-fields of condensed matter physics, with central relevance to an understanding of electronic conduction, charge density wave physics, and topological properties.  We derive a connection between the momentum distribution backfolding procedure of Lock, Crisp, and West with the eigenvalues of the one body reduced density matrix of an interacting ground state wavefunction. Finite discontinuities in the resulting occupation number distribution in the first Brillouin zone gives direct access to the structure of the Fermi surface for both simple and correlated metals. We demonstrate this connection in the high mobility quasi-2D conductor PdCoO₂ via direct comparison between ARPES and the Fermi surface obtained by many body quantum Monte Carlo techniques.

* This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, as part of the Computational Materials Sciences Program and Center for Predictive Simulation of Functional Materials.