The goal of this program was to obtain total energies
accurate to 1 microHartree across the periodic table
(compared to an RLDA total energy of -28001 Hartree for U),
a value which seems thoroughly
adequate for all forseeable needs of materials science and
chemistry (1 microHartree = 0.03 meV = 0.0006 kcal/mole).

Obviously, this goal could only be attained by performing complex
numerical calculations, for which it is difficult to
state an error budget in rigorous quantitative terms.
The only exact analytical results available to us are the total
energies (equal to orbital energy eigenvalues) of one-electron
atoms, as given by solution of the
Schrödinger equation. We found that, in all cases, these
energies were reproduced to the numerical accuracy of the
computer for radial grid parameters similar to those
used in our production runs.

Thus, our basis for quoting
the absolute numerical accuracies given here derives from

- establishing the accuracy of one-electron calculations, and
- observing consensus of the results of independent calculations (quantified in the following figures), which were seen to improve systematically as the numerical grids were refined.