  A method is developed that allows analysis of quantum Monte Carlo simulations
to identify errors in trial wave functions. The purpose of this method is to
allow for the systematic improvement of variational wave functions by
identifying degrees of freedom that are not well-described by an initial trial
state. We provide proof of concept implementations of this method by
identifying the need for a Jastrow correlation factor, and implementing a
selected multi-determinant wave function algorithm for small dimers that
systematically decreases the variational energy. Selection of the two-particle
excitations is done using quantum Monte Carlo within the presence of a Jastrow
correlation factor, and without the need to explicitly construct the
determinants. We also show how this technique can be used to design compact
wave functions for transition metal systems. This method may provide a route to
analyze and systematically improve descriptions of complex quantum systems in a
scalable way.
