Multiconfiguration Pair-Density Functional Theory and Complete Active Space Second Order Perturbation Theory. Bond Dissociation Energies of FeC, NiC, FeS, NiS, FeSe, and NiSe

Sharkas, Kamal; Gagliardi, Laura; Truhlar, Donald G.

doi:10.1021/acs.jpca.7b09779

Cited by 32 publications

(26 citation statements)

References 76 publications

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“…Here, we compare the accuracy of using CAS-PDFT and SP-PDFT on a set of 25 diatomic molecules containing one or two transition metal atoms. This includes the three molecules studied in the present paper (VSi, NbSi, TaSi) and 22 studied previously [ 16 , 17 , 29 ]. All 25 data points in this comparison are transition metal diatomic BDEs calculated with a nom-CPO active space [ 16 , 17 , 29 ].…”

Section: Resultsmentioning

confidence: 99%

“…The generalized active space self-consistent field method [ 14 ] was introduced to reduce computational cost by partitioning the active space into subspaces. The partitioning may be done by various schemes, and the present study uses the scheme of the separated-pair (SP) approximation [ 15 , 16 , 17 ]. The SP approximation is like generalized valence bond theory [ 18 ] but without the perfect pairing approximation.…”

Section: Introductionmentioning

confidence: 99%

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Multiconfiguration Pair-Density Functional Theory for Transition Metal Silicide Bond Dissociation Energies, Bond Lengths, and State Orderings

2021

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Transition metal silicides are promising materials for improved electronic devices, and this motivates achieving a better understanding of transition metal bonds to silicon. Here we model the ground and excited state bond dissociations of VSi, NbSi, and TaSi using a complete active space (CAS) wave function and a separated-pair (SP) wave function combined with two post-self-consistent field techniques: complete active space with perturbation theory at second order and multiconfiguration pair-density functional theory. The SP approximation is a multiconfiguration self-consistent field method with a selection of configurations based on generalized valence bond theory without the perfect pairing approximation. For both CAS and SP, the active-space composition corresponds to the nominal correlated-participating-orbital scheme. The ground state and low-lying excited states are explored to predict the state ordering for each molecule, and potential energy curves are calculated for the ground state to compare to experiment. The experimental bond dissociation energies of the three diatomic molecules are predicted with eight on-top pair-density functionals with a typical error of 0.2 eV for a CAS wave function and a typical error of 0.3 eV for the SP approximation. We also provide a survey of the accuracy achieved by the SP and extended separated-pair approximations for a broader set of 25 transition metal–ligand bond dissociation energies.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multiconfiguration Pair-Density Functional Theory for Transition Metal Silicide Bond Dissociation Energies, Bond Lengths, and State Orderings

2021

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“…8 For transition metals, the challenge is compounded by uncertainties in many of the experimental measurements used as relevant test cases, as is apparent in recent investigations using a variety of computational methods on small molecules. [9][10][11][12][13][14][15][16][17][18][19] Focusing on CC methods, electronic excitations for atoms are well described by CCSD(T) calculations using large basis sets and correcting for relativistic effects. 8 However, even for problems involving simple diatomic molecules, such as the dissociation energy of NiH, there is considerable uncertainty as to the degree of accuracy that CCSD(T) methods can achieve.…”

Section: Introductionmentioning

confidence: 99%

On Achieving High Accuracy in Quantum Chemical Calculations of 3d Transition Metal-Containing Systems: A Comparison of Auxiliary-Field Quantum Monte Carlo with Coupled Cluster, Density Functional Theory, and Experiment for Diatomic Molecules

Shee

Rudshteyn

Arthur

et al. 2019

J. Chem. Theory Comput.

117

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The bond dissociation energies of a set of 44 3d transition metal-containing diatomics are computed with phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC) utilizing a correlated sampling technique. We investigate molecules with H, N, O, F, Cl, and S ligands, including those in the 3dMLBE20 database first compiled by Truhlar and co-workers with calculated and experimental values that have since been revised by various groups. In order to make a direct comparison of the accuracy of our ph-AFQMC calculations with previously published results from 10 DFT functionals, CCSD(T), and icMR-CCSD(T), we establish an objective selection protocol which utilizes the most recent experimental results except for a few cases with well-specified discrepancies. With 1 arXiv:1901.09464v1 [physics.chem-ph] 27 Jan 2019 the remaining set of 41 molecules, we find that ph-AFQMC gives robust agreement with experiment superior to that of all other methods, with a mean absolute error (MAE) of 1.4(4) kcal/mol and maximum error of 3(3) kcal/mol (parenthesis account for reported experimental uncertainties and the statistical errors of our ph-AFQMC calculations).In comparison, CCSD(T) and B97, the best performing DFT functional considered here, have MAEs of 2.8 and 3.7 kcal/mol, respectively, and maximum errors in excess of 17 kcal/mol for both methods. While a larger and more diverse data set would be required to demonstrate that ph-AFQMC is truly a benchmark method for transition metal systems, our results indicate that the method has tremendous potential, exhibiting unprecedented consistency and accuracy compared to other approximate quantum chemical approaches.

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“…The pronounced lack of reliable and precise gas-phase experimental data for realistic transition metal systems, as illustrated by recent theoretical benchmarking studies, exacerbates these issues. [19][20][21][22][23][24][25][26][27][28][29] This scarcity of experimental measurements is in stark contrast to the large amount of reliable experimental values for organic molecules, which has enabled very accurate parameterizations of DFT functionals and a thorough validation of methods such as CCSD(T), which can readily achieve ∼1 kcal/mol accuracy for typical organic molecules. 30 The accuracy of CC methods, most frequently CCSD(T), is often assumed to carry over to transition metal systems, as evidenced by a number of studies that have attempted to draw conclusions about the accuracy of DFT by comparing against reference CC values.…”

Section: Introductionmentioning

confidence: 99%

Predicting Ligand-Dissociation Energies of 3d Coordination Complexes with Auxiliary-Field Quantum Monte Carlo

Rudshteyn

Coskun

Weber

et al. 2020

J. Chem. Theory Comput.

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Transition metal complexes are ubiquitous in biology and chemical catalysis, yet they remain difficult to accurately describe with ab initio methods due to the presence of a large degree of dynamic electron correlation, and, in some cases, strong static correlation which results from a manifold of low-lying states. Progress has been hindered by a scarcity of high quality gas-phase experimental data, while exact ab initio predictions are usually computationally unaffordable due to the large size of the relevant complexes.In this work, we present a data set of 34 tetrahedral, square planar, and octahedral 3d metal-containing complexes with gas-phase ligand-dissociation energies that have reported uncertainties of ≤ 2 kcal/mol. We perform all-electron phaseless auxiliaryfield quantum Monte Carlo (ph-AFQMC) calculations utilizing multi-determinant trial wavefunctions selected by a blackbox procedure. We compare the results with those from density functional theory (DFT) with the B3LYP, B97, M06, PBE0, ωB97X-V, and DSD-PBEP86/2013 functionals, and a localized orbital variant of coupled cluster theory with single, double, and perturbative triple excitations (DLPNO-CCSD(T)). We find mean averaged errors of 1.09 ± 0.28 kcal/mol for our best ph-AFQMC method, vs 2.89 kcal/mol for DLPNO-CCSD(T) and 1.57 -3.87 kcal/mol for DFT. We find maximum errors of 2.96 ± 1.71 kcal/mol for our best ph-AFQMC method, vs 9.15 kcal/mol for DLPNO-CCSD(T) and 5.98 -13.69 kcal/mol for DFT. The reasonable performance of a number of DFT functionals is in stark contrast to the much poorer accuracy previously demonstrated for diatomic species, suggesting a moderation in electron correlation due to ligand coordination. However, the unpredictably large errors for a small subset of cases with both DFT and DLPNO-CCSD(T) methods leave cause for concern, especially in light of the unreliability of common multi-reference indicators. In contrast, the robust and, in principle, systematically improvable results of ph-AFQMC for these realistic complexes establish the method as a useful tool for elucidating the electronic structure of transition metal-containing complexes and predicting their gas-phase properties.

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Multiconfiguration Pair-Density Functional Theory and Complete Active Space Second Order Perturbation Theory. Bond Dissociation Energies of FeC, NiC, FeS, NiS, FeSe, and NiSe

Cited by 32 publications

References 76 publications

Multiconfiguration Pair-Density Functional Theory for Transition Metal Silicide Bond Dissociation Energies, Bond Lengths, and State Orderings

Multiconfiguration Pair-Density Functional Theory for Transition Metal Silicide Bond Dissociation Energies, Bond Lengths, and State Orderings

On Achieving High Accuracy in Quantum Chemical Calculations of 3d Transition Metal-Containing Systems: A Comparison of Auxiliary-Field Quantum Monte Carlo with Coupled Cluster, Density Functional Theory, and Experiment for Diatomic Molecules

Predicting Ligand-Dissociation Energies of 3d Coordination Complexes with Auxiliary-Field Quantum Monte Carlo

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