A larger basis set describes atomization energy core-valence correction better than a higher-order coupled-cluster method

14 August 2023, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


The accuracy of coupled-cluster methods for the computation of core-valence correction to atomization energy was assessed. Truncation levels up to CCSDTQP were considered together with (aug-)cc-pwCVnZ (n = D, T, Q, 5) basis sets and three different extrapolation techniques (canonical and flexible Helgaker formula and Riemann zeta function extrapolation). With the exception of CCSD, a more accurate correction can be obtained from a larger basis set with a lower-level coupled-cluster method, and not vice versa. For the CCSD(T) level, it also implies faster computations with modern codes. We also discussed the importance of moving to higher-order or all-electron methods for geometry optimizations. The present study provides the general knowledge needed for the most accurate state-of-the-art computations.


core-valence correction
coupled cluster
higher-order method
CBS extrapolation

Supplementary materials

Supporting information.
Detailed raw and processed energies, cartesian coordinates of optimized structures.


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