Comparing performance with QMCPACK

The key kernels from QMCPACK are present in miniQMC, but the relative importance of each kernel may not be retained.

The inverse determinant update is an N^3 operation, and increasingly dominates the run time as the system size increases. In miniQMC, the timer is Update/Determinant. In QMCPACK, the timer is DiracDeterminantBase::update

The acceptance ratio option (-r) affects the number of inverse updates performed. The default setting is 0.5, which corresponds the acceptance ratio of a VMC run. To more accurately reproduce a DMC run, use an acceptance ratio 0.99 (-r 0.99)