Approximating a Wavefunction as an Unconstrained Sum of Slater Determinants

The simplest construction of an antisymmetric function of many variables is as a Slater determinant. We present a method for approximating the wavefunction with an unconstrained sum of such Slater determinants. Removal of constraints may allow significantly more efficient representations and computations than current methods provide. The resulting representations also present a different perspective from which to understand the wavefunction.