Mester Dávid, Nagy Péter R, Kállay Mihály
Department of Physical Chemistry and Materials Science, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Muegyetem rkp. 3, H-1111 Budapest, Hungary.
HUN-REN-BME Quantum Chemistry Research Group, Muegyetem rkp. 3, H-1111 Budapest, Hungary.
J Chem Theory Comput. 2024 Sep 10;20(17):7453-7468. doi: 10.1021/acs.jctc.4c00777. Epub 2024 Aug 29.
The calculation of density-based basis-set correction (DBBSC), which remedies the basis-set incompleteness (BSI) error of the correlation energy, is combined with local approximations. Aiming at large-scale applications, the procedure is implemented in our efficient local natural orbital-based coupled-cluster singles and doubles with perturbative triples [LNO-CCSD(T)] scheme. To this end, the range-separation function, which characterizes the one-electron BSI in space, is decomposed into the sum of contributions from individual localized molecular orbitals (LMOs). A compact domain is constructed around each LMO, and the corresponding contributions are evaluated only within these restricted domains. Furthermore, for the calculation of the complementary auxiliary basis set (CABS) correction, which significantly improves the Hartree-Fock (HF) energy, the local density fitting approximation is utilized. The errors arising from the local approximations are examined in detail, efficient prescreening techniques are introduced to compress the numerical quadrature used for DBBSC, and conservative default thresholds are selected for the truncation parameters. The efficiency of the DBBSC-LNO-CCSD(T) method is demonstrated through representative examples of up to 1000 atoms. Based on the numerical results, we conclude that the corrections drastically reduce the BSI error using double-ζ basis sets, often to below 1 kcal/mol compared to the reliable LNO-CCSD(T) complete basis set references, while significant improvements are also achieved with triple-ζ basis sets. Considering that the calculation of the DBBSC and CABS corrections only moderately increases the wall-clock time required for the post-HF steps in practical applications, the proposed DBBSC-LNO-CCSD(T) method offers a highly efficient and robust tool for large-scale calculations.
基于密度的基组校正（DBBSC）用于弥补相关能的基组不完备（BSI）误差，它与局部近似相结合。针对大规模应用，该方法在我们高效的基于局部自然轨道的耦合簇单双激发微扰三重激发[LNO-CCSD(T)]方案中得以实现。为此，表征空间中单电子BSI的范围分离函数被分解为各个定域分子轨道（LMO）贡献的总和。围绕每个LMO构建一个紧凑区域，并且仅在这些受限区域内评估相应的贡献。此外，为了计算能显著提高哈特里-福克（HF）能量的互补辅助基组（CABS）校正，采用了局部密度拟合近似。详细研究了局部近似产生的误差，引入了有效的预筛选技术来压缩用于DBBSC的数值积分，并为截断参数选择了保守的默认阈值。通过多达1000个原子的代表性示例证明了DBBSC-LNO-CCSD(T)方法的效率。基于数值结果，我们得出结论，使用双ζ基组时，这些校正极大地降低了BSI误差，与可靠的LNO-CCSD(T)完备基组参考相比，通常降至1 kcal/mol以下，而使用三ζ基组也取得了显著改进。考虑到在实际应用中DBBSC和CABS校正的计算仅适度增加了后HF步骤所需的时钟时间，所提出的DBBSC-LNO-CCSD(T)方法为大规模计算提供了一种高效且稳健的工具。
