Performance of Localized-Orbital Coupled-Cluster Approaches for the Conformational Energies of Longer n-Alkane Chains

• Published in: The Journal of Physical Chemistry A
• Main Authors: Santra, Golokesh, Martin, Jan M.L.
• Format: Text
• Language: English
• Published: American Chemical Society 2022
• Subjects: Orca
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9791657/; http://www.ncbi.nlm.nih.gov/pubmed/36508714; https://doi.org/10.1021/acs.jpca.2c06407

[Image: see text] We report an update and enhancement of the ACONFL (conformer energies of large alkanes [J. Phys. Chem. A2022,126, 3521–3535]) dataset. For the ACONF12 (n-dodecane) subset, we report basis set limit canonical coupled-cluster with singles, doubles, and perturbative triples [i.e., CCSD(T)] reference data obtained from the MP2-F12/cc-pV{T,Q}Z-F12 extrapolation, [CCSD(F12*)-MP2-F12]/aug-cc-pVTZ-F12, and a (T) correction from conventional CCSD(T)/aug-cc-pV{D,T}Z calculations. Then, we explored the performance of a variety of single and composite localized-orbital CCSD(T) approximations, ultimately finding an affordable localized natural orbital CCSD(T) [LNO-CCSD(T)]-based post-MP2 correction that agrees to 0.006 kcal/mol mean absolute deviation with the revised canonical reference data. In tandem with canonical MP2-F12 complete basis set extrapolation, this was then used to re-evaluate the ACONF16 and ACONF20 subsets for n-hexadecane and n-icosane, respectively. Combining those with the revised canonical reference data for the dodecane conformers (i.e., ACONF12 subset), a revised ACONFL set was obtained. It was then used to assess the performance of different localized-orbital coupled-cluster approaches, such as pair natural orbital localized CCSD(T) [PNO-LCCSD(T)] as implemented in MOLPRO, DLPNO-CCSD(T(0)) and DLPNO-CCSD(T(1)) as implemented in ORCA, and LNO-CCSD(T) as implemented in MRCC, at their respective “Normal”, “Tight”, “vTight”, and “vvTight” accuracy settings. For a given accuracy threshold and basis set, DLPNO-CCSD(T(1)) and DLPNO-CCSD(T(0)) perform comparably. With “VeryTightPNO” cutoffs, explicitly correlated DLPNO-CCSD(T(1))-F12/VDZ-F12 is the best pick among all the DLPNO-based methods tested. To isolate basis set incompleteness from localized-orbital-related truncation errors (domain, LNOs), we have also compared the localized coupled-cluster approaches with canonical DF-CCSD(T)/aug-cc-pVTZ for the ACONF12 set. We found that gradually tightening the cutoffs improves the performance ...