Convergence thresholds for CCSD equations are summarized in Table . Since single precision provides ∼7 decimal digits of precision, the tightest threshold of convergence for energy in single precision is 10 -7 hartree (assuming correlation energies of 1 hartree). By numerical experimentation we found that single precision iterations converge smoothly with energy threshold of 10 -5 -10 -6 hartree; therefore, we used this threshold for the single precision part of the calculation in most cases. In the double-precision calculations, we used default convergence except for the benzene benchmark. In properties calculations, we used the same convergence criteria for T and Λ amplitudes. Unrelaxed one-particle density matrices used in dipole moment calculations were computed in double and single precision from respective double and single precision intermediates and amplitudes. In all EOM calculations a 10 -5 convergence threshold for EOM amplitudes was used in the Davidson procedure. For geometry optimization and finite-difference frequency analysis, much tighter convergence criteria were used: 10 -10 for energies, 10 -9 for T and Λ amplitudes for double precision; 10 -7 for energies, 10 -5 for T and Λ amplitudes for single precision. The criteria of convergence in geometry optimization were the same for the double and single precision calculations: 2 • 10 -5 a.u. for the maximum component of the gradient 5 • 10 -5 a.u. for the maximum atomic displacement, and 1 • 10 -7 a.u. for energy.