Assessment of a semi integral-direct local multi-reference configuration interaction implementation employing shared-memory parallelization

Dieterich, Johannes M.; Carter, Emily A.

doi:10.1016/j.comptc.2014.10.030

Cited by 9 publications

(16 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similarly, RCCSD(T) and UCCSD(T) were utilized for closed-shell and open-shell species, respectively. Given the relatively high multi-configurational character of these species (vide infra), we also used MRSDCI with the DS correction and MRACPF2 theories to obtain the stationary energies using the MOLCAS 38 and TIGERCI [39][40][41][42][43][44][45][46][47] codes with basis sets cc-pVXZ (X = D, T). For dissociated fragments in the multi-reference methods, a super-molecule scheme with two fragments about 10 Å apart was used to ensure size-consistency.…”

Section: Computational Methods and Detailsmentioning

confidence: 99%

Ab initio pressure-dependent reaction kinetics of methyl propanoate radicals

Tan

Yang

et al. 2015

Phys. Chem. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

The unimolecular dissociation and isomerization kinetics of the three methyl propanoate (MP) radicals, CH3CH2C(=O)OĊH2 (MP-m), CH3ĊHC(=O)OCH3 (MP-α), and ĊH2CH2C(=O)OCH3 (MP-β), are theoretically investigated using high-level ab initio methods and the Rice-Ramsperger-Kassel-Marcus (RRKM)/master equation (ME) theory. Stationary-point energies are obtained using the coupled cluster singles and doubles with perturbative triples correction (CCSD(T)), multi-reference singles and doubles configuration interaction (MRSDCI) with the Davidson-Silver (DS) correction, and multi-reference averaged coupled pair functional (MRACPF2) theories. The isomerization barriers between the three radicals are predicted to be generally lower than the corresponding bond dissociation channels, leading to a strongly coupled reaction system in subsequent kinetics studies. The phenomenological temperature- and pressure-dependent rate coefficients are computed using the RRKM/ME theory over a temperature range of 500 to 2000 K and at a pressure range of 0.01 atm to the high-pressure limit, which are then fitted to modified Arrhenius expressions. The β-scission rate coefficients of MP-α to CH3CHC(=O) and CH3O[combining dot above] are predicted to be the smallest because of its highest activation energy among all studied unimolecular reactions channels. Analysis of branching fractions shows that both MP-m and MP-α radicals mainly decompose to the bimolecular products CH3CH2Ċ(=O) and H2CO, whereas the MP-β radical primarily decomposes via cleavage of a C-C bond to form C2H4 and CH3OĊ(=O). The isomerization channels dominate at low temperatures, the branching fractions of which decrease with increasing temperature and become very minor at about 2000 K. Our accurate rate coefficients and branching fractions help to illuminate the unique combustion properties of MP.

show abstract

Section: Computational Methods and Detailsmentioning

confidence: 99%

Ab initio pressure-dependent reaction kinetics of methyl propanoate radicals

Tan

Yang

et al. 2015

Phys. Chem. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The calculated BDEs of eight different bonds, represented as reactions Rx1−Rx8, are compared with the MRACPF2 results reported by Carter and co-workers. 38,39 The BDEs of methyl linolenate reported by them were computed by combining the dissociation energies of smaller surrogates, for example, methyl butanoate, 1,4-pentadiene, 3-hexene, and 1-pentene. 18 The MAD obtained for both CBH-2 and CBH-3 schemes are within our target accuracy of 2 kcal/mol.…”

Section: Resultsmentioning

confidence: 99%

“…The steep scaling of accurate quantum chemical methods, such as the “gold-standard” CCSD(T), coupled with the need to examine multiple elementary combustion pathways of biodiesel esters have restricted many of these studies to smaller surrogate systems , such as methyl butanoate (C 3 H 7 COOCH 3 ). , Nevertheless, two groups have recently carried out significant studies on both small and large methyl esters. Carter and co-workers , applied a multireference averaged coupled-pair functional method (MRACPF) and an improved MRACPF2 model to compute BDEs of the different bonds in C1–C4 methyl esters acting as surrogates of biodiesel esters. , The calculated values were found to be in good agreement with multireference singles and doubles configuration interaction (MRSDCI) results. A local reduced-scaling variant developed by Carter and co-workers , was then applied on C 10 and C 18 esters to derive their thermochemical properties .…”

Section: Introductionmentioning

confidence: 82%

“…36,37 The calculated values were found to be in good agreement with multireference singles and doubles configuration interaction (MRSDCI) results. A local reduced-scaling variant developed by Carter and co-workers 38,39 was then applied on C 10 and C 18 esters to derive their thermochemical properties. 18 In general, the calculated BDEs were largely consistent with those obtained from the earlier calculations on ester surrogates.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Eliminating Systematic Errors in DFT via Connectivity-Based Hierarchy: Accurate Bond Dissociation Energies of Biodiesel Methyl Esters

2019

View full text Add to dashboard Cite

We present a computational study focusing on the determination of accurate bond dissociation energies (BDEs) involved in the combustion of biodiesel methyl esters. We have adapted our previously developed efficient error-cancellation protocols, based on the systematic "connectivity-based hierarchy" (CBH), to derive accurate BDEs of biodiesel molecules at a modest computational cost. Using DFT energies on the full biodiesel molecule in conjunction with accurate G4 energies on the small fragments involved in the CBH reaction schemes, systematic errors in the DFT methods can be cancelled efficiently. Herein, we apply our G4corrected ΔCBH-2 and ΔCBH-3 schemes in conjunction with several popular DFT methods to determine accurate bond dissociation energies of different C−C, C−H, and C−O bonds in biodiesel surrogate molecules. We first evaluate the performance of different DFT methods using a test set of 21 reactions involving various bond dissociations in small to medium biodiesel surrogates (up to methyl decanoate, a C10-methyl ester) by calibration against accurate values calculated with multireference methods (MRACPF2), reported by Carter and co-workers. The CBH-2 corrections for all tested dispersion-corrected functionals yield mean absolute deviations (MADs) in a narrow range of 1.3−1.5 kcal/mol, the best performance being obtained for B97-D3 and ωB97X-D functionals (MAD = 1.3 kcal/mol). Further, significant improvement yielding a MAD of only 0.9 kcal/mol is obtained using the G4-corrected CBH-3 scheme. Finally, the protocol has been applied to derive accurate BDEs of eight different bonds in the larger biodiesel molecule, methyl linolenate, yielding a MAD of only 1.13 kcal/mol using the ΔCBH-3 error correction scheme. The results suggest that our protocol in conjunction with different DFT methods should be broadly applicable to yield accurate BDEs for a variety of large biodiesel molecules.

show abstract

“…The breakthrough arrived in 2003 with a paper by Koch et al presenting the first fully fledged implementation of the CD approximation within Hartree-Fock (HF) and second-order Møller-Plesset perturbation theory (MP2). 6 Since this first general implementation the CD approximation has been used in many computational chemistry studies, [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] and it is now available within several quantum chemistry packages for a wide range of electronic structure methods, including density-functional theory (DFT) and HF, 6,25,26 multiconfigurational secondorder perturbation theory (CASSCF/CASPT2), [27][28][29] multireference configuration interaction, [30][31][32][33] Møller-Plesset perturbation theory, 6,[34][35][36] Coupled Cluster (CC) theory, [37][38][39][40] electron propagator methods, 41 symmetry-adapted perturbation theory, 42 fragment molecular orbital theory, 43 and quantum Monte Carlo. 44 The use of CD-based algorithms has made possible nowadays calculations at the correlated level with thousands of basis functions,...…”

Section: Introductionmentioning

confidence: 99%

Inner projection techniques for the low-cost handling of two-electron integrals in quantum chemistry

et al. 2017

View full text Add to dashboard Cite

The density fitting technique for approximating electron repulsion integrals relies on the quality of auxiliary basis sets. These are commonly obtained through data fitting, an approach that presents some shortcomings. On the other hand, it is possible to derive auxiliary basis sets by removing elements from the product 1 space of both contracted and primitive orbitals by means of a particular form of inner projection technique that has come to be known as Cholesky decomposition (CD). This procedure allows for on-the-fly construction of auxiliary basis sets that may be used in conjunction with any quantum chemical method, i.e., unbiased auxiliary basis sets. One key feature of these sets is that they represent the electron repulsion integral matrix in atomic orbital basis with an accuracy that can be systematically improved by lowering the threshold for approximate linear dependences-in the sense of a Coulomb metric ("1/r 12 "). Another key feature is represented by the fact that locality of fitting coefficients is obtained even with the long-ranged Coulomb metric, as result of integral accuracy. Here we report on recent advances in the development of the CD-based DF technology. In particular, the implementation of analytical gradients algorithms is reviewed and the present status of local formulations-potentially linear scaling-is analyzed in great details.

show abstract

Assessment of a semi integral-direct local multi-reference configuration interaction implementation employing shared-memory parallelization

Cited by 9 publications

References 32 publications

Ab initio pressure-dependent reaction kinetics of methyl propanoate radicals

Ab initio pressure-dependent reaction kinetics of methyl propanoate radicals

Eliminating Systematic Errors in DFT via Connectivity-Based Hierarchy: Accurate Bond Dissociation Energies of Biodiesel Methyl Esters

Inner projection techniques for the low-cost handling of two-electron integrals in quantum chemistry

Contact Info

Product

Resources

About