Explicitly Correlated Local Electron Correlation Methods

Werner, Hans‐Joachim; Köppl, Christoph; Schwilk, Max

doi:10.1002/9781119129271.ch1

Cited by 18 publications

(30 citation statements)

References 141 publications

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“…Fourth, the minimal-basis implementation developed here could be extended to perform FVAS calculations to recover the valence electron correlation in larger basis sets (e.g., applying BE to the subspace spanned by localized valence orbitals). The remaining electron correlation, mainly weak and dynamic in nature, could potentially be described at a low cost by perturbation theory . In addition, although the fixed RHF bath works well in this work, there are cases where the quality of the bath is important. , Thus, one can either adopt a better bath wave function , or perform explicit bath optimization .…”

Section: Discussionmentioning

confidence: 96%

Bootstrap Embedding For Large Molecular Systems

Tran

Voorhis

2020

J. Chem. Theory Comput.

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Recent developments in quantum embedding theories have provided attractive approaches to correlated calculations for large systems. In this work, we extend our previous work [J. Chem. Theory Comput. 2019, 15, 4497–4506; J. Phys. Chem. Lett. 2019, 10, 6368–6374] on bootstrap embedding (BE) to enable correlated ab initio calculations at the coupled cluster with singles and doubles (CCSD) level for large molecules. We introduce several new algorithmic developments that significantly reduce the computational cost of BE, while maintaining its accuracy. The resulting implementation scales as O(N 3) for the integral transform and O(N) for the CCSD calculation. Numerical results on a series of conjugated molecules suggest that BE with reasonably sized fragments can recover more than 99.5% of the total correlation energy of a full CCSD calculation, while the required computational resources (time and storage) compare favorably to one popular local correlation scheme: domain localized pair natural orbital (DLPNO). The largest BE calculation in this work involves ∼2900 basis functions and can be performed on a single node with 16 CPU cores and 64 GB of memory in a few days. We anticipate that these developments represent an important step toward the application of BE to solve practical problems.

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Section: Discussionmentioning

confidence: 96%

Bootstrap Embedding For Large Molecular Systems

Tran

Voorhis

2020

J. Chem. Theory Comput.

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“…the atom that the lone pair sits on. 31,36 In contrast, ORCA uses an orbital population (older version) or orbital overlap (newer version) based criterion. In the older version, 21,19 all atoms for which the orbital had a Mulliken population greater in absolute value than TCutMKN were included in the domain; whereas in ORCA 4 and later, 37 the orbital is included if the square root of the differential overlap is greater than TCutDO.…”

Section: Dlpno-ccsd(t)mentioning

confidence: 99%

Performance of Localized Coupled Cluster Methods in a Moderately Strong Correlation Regime: Hückel–Möbius Interconversions in Expanded Porphyrins

Sylvetsky

Banerjee

Alonso

et al. 2020

J. Chem. Theory Comput.

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KEYWORDS expanded porphyrins • topology interconversions • localized coupled cluster • canonical coupled cluster • nondynamical correlation ABSTRACT Localized orbital coupled cluster theory has recently emerged as a nonempirical alternative to DFT for large systems. Intuitively, one might expect such methods to perform less well for highly delocalized systems. In the present work, we apply both canonical CCSD(T) and a variety of localized approximations thereto to a set of flexible expanded porphyrinsmacrocycles that can switch between Hückel, figure-eight, and Möbius topologies under external stimuli. Both minima and isomerization transition states are considered. We find that Möbius(-like) structures have much stronger static correlation character than the remaining structures, and this causes significant errors in DLPNO-CCSD(T) and even DLPNO-CCSD(T1) approaches, unless TightPNO cutoffs are employed. If sub-kcal mol -1 accuracy with respect to canonical relative energies is required even for Möbius-type systems (or other systems plagued by strong static correlation), then Nagy and Kallay's LNO-CCSD(T) method with "tight" settings is the suitable localized approach. We propose the present POLYPYR21 dataset as a benchmark for localized orbital methods, or more broadly, for the ability of lower-level methods to handle energetics with strongly varying degrees of static correlation.

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“…A sufficient degree of electron correlation, such as in the coupled cluster singles and doubles (CCSD) approach, is typically capable of reproducing gas-phase experimental optical rotatory dispersion curves for most systems studied to date, but the high-degree polynomial scaling associated with such accurate correlated wave function methods (e.g., for CCSD) is problematic for large molecules and/or cases of high sensitivity to the choice of the one-electron basis set. − Indeed, large, flexible, atomic-orbital (AO) basis sets augmented with diffuse functions are required to obtain converged specific rotation values for many molecules. Furthermore, this high computational cost is exacerbated for flexible molecules where conformational sampling is needed , and in cases where vibrational corrections are significant. , While one may seek to ameliorate such costs by choosing less expensive electron correlation models (e.g., the second-order approximate coupled cluster singles and doubles method (CC2), − which scales as ]) or by employing local-correlation or other reduced-scaling techniques, − such methods still depend on the use of effective and efficient AO basis sets …”

Section: Introductionmentioning

confidence: 99%

Performance of Property-Optimized Basis Sets for Optical Rotation with Coupled Cluster Theory

et al. 2018

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The effectiveness of the optical rotation prediction (ORP) basis set for computing specific rotations at the coupled cluster (CC) level has been evaluated for a test set of 14 chiral compounds. For this purpose, the ORP basis set has been developed for the second-row atoms present in the investigated systems (that is, for sulfur, phosphorus, and chlorine). The quality of the resulting set was preliminarily evaluated for seven molecules using time-dependent density-functional theory (TD-DFT). Rotations were calculated with the coupled cluster singles and doubles method (CCSD) as well as the second-order approximate coupled cluster singles and doubles method (CC2) with the correlation-consistent aug-cc-pVDZ and aug-cc-pVTZ basis sets and extrapolated to estimate the complete basis-set (CBS) limit for comparison with the ORP basis set. In the compounds examined here, the ORP calculations on molecules containing only first-row atoms compare favorably with results from the larger aug-cc-pVTZ basis set, in some cases lying closer to the estimated CBS limit, while results for molecules containing second-row atoms indicate that larger correlation-consistent basis sets are necessary to obtain reliable estimates of the CBS limit.

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Explicitly Correlated Local Electron Correlation Methods

Cited by 18 publications

References 141 publications

Bootstrap Embedding For Large Molecular Systems

Bootstrap Embedding For Large Molecular Systems

Performance of Localized Coupled Cluster Methods in a Moderately Strong Correlation Regime: Hückel–Möbius Interconversions in Expanded Porphyrins

Performance of Property-Optimized Basis Sets for Optical Rotation with Coupled Cluster Theory

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