Figure shows how the error in total RPA correlation energy of several types of materials varies when 4, 8, 12, 16, and 20 imaginary frequencies are in the quadrature. Overall, the RPA correlation energies converged within 1 meV/atom for all materials when 12 imaginary frequencies are used. The error was not strongly impacted by dimensionality of the material, with the molecules and small bulk materials converging similarly quickly. The per atom errors for the 1 and 2 atom bulk Pt systems are nearly identical, showing that this error is size extensive and that taking energy differences between similarly sized systems, as in done for adsorption energies, will help cancel this error. We note that a more conservative 16 imaginary frequencies were used for the benchmarking calculations in this work, but that 12 frequencies were used for RPA calculations on the surfaces in the final subsection.