utilized by the majority of past research that has examined the benchmark being studied, thus enabling direct comparisons of results. In order to guarantee accurate gradients, we used the TIGHTINT keyword in QUICK, which requests tight numerical cutoffs and SCF convergence. With these settings, the root-mean-square (RMS) change in the density matrix is less than 10 -7 au and the maximum change in the density matrix is less than 10 -5 au. In order to compare different geometry optimizers, a test suite of 30 molecules as depicted in In both cases Baker employed the unit matrix as the initial Hessian. Using an initial Hessian from a molecular mechanics model, Baker managed to further reduce the number of steps to 240 (on average 8 steps per molecule). This data is not shown in Table but the numbers should be kept in mind for the following discussion.