First- and Second-Order Density Matrices of Symmetry-Projected Single-Determinant Wavefunctions

Abstract
We derive the first- and second-order density matrices of symmetry-projected single-determinant wavefunctions, in the case of finite groups. We also give the first-order density matrices for functions projected in the axial-rotation group. A method is presented for extracting from a density matrix its totally symmetric component, and the eigenfunctions of this component are shown to be the same after projection as before.