Revisiting the extrapolation of correlation energies to complete basis set limit

The extrapolation scheme of correlation energy is revisited to evaluate the complete basis set limit from double‐zeta (DZ) and triple‐zeta levels of calculations. The DZ level results are adjusted to the standard asymptotic behavior with respect to the cardinal number, observed at the higher levels of basis sets. Two types of adjusting schemes with effective scaling factors, which recover errors in extrapolations with the DZ level basis set, are examined. The first scheme scales the cardinal number for the DZ level energy, while the second scheme scales the prefactor of the extrapolation function. Systematic assessments on the Gaussian‐3X and Gaussian‐2 test sets reveal that these calibration schemes successfully and drastically reduce errors without additional computational efforts. © 2015 Wiley Periodicals, Inc. The extrapolation scheme of correlation energy is revisited in order to evaluate the complete basis set (CBS) limit from double‐zeta and triple‐zeta levels of calculations. The newly proposed scheme with the scaling factor, which is determined in an empirical manner, successfully reproduces both the CBS limit energy and the shape of the extrapolation curve, observed at the higher levels of basis sets, without additional computational effort.