scholarly journals BH9, a New Comprehensive Benchmark Dataset for Barrier Heights and Reaction Energies: Assessment of Density Functional Approximations and Basis Set Incompleteness Potentials

2021 ◽  
Author(s):  
Viki Kumar Prasad ◽  
Zhipeng Pei ◽  
Simon Edelmann ◽  
Alberto Otero-de-la-Roza ◽  
Gino DiLabio
Keyword(s):  
Density Functional ◽  
Benchmark Dataset ◽  
Basis Set ◽  
Barrier Heights ◽  
Reaction Energies

Evaluating Transition Metal Barrier Heights with the Latest DFT Exchange–Correlation Functionals – the MOBH35 Benchmark Dataset

2019 ◽  
Author(s):  
Mark Iron ◽  
Trevor Janes
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Computational Cost ◽  
Basis Set ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Barrier Heights ◽  
Complete Basis Set ◽  
Complete Basis Set Limit ◽  
Hybrid Functionals

A new database of transition metal reaction barrier heights – MOBH35 – is presented. Benchmark energies (forward and reverse barriers and reaction energy) are calculated using DLPNO-CCSD(T) extrapolated to the complete basis set limit using a Weizmann1-like scheme. Using these benchmark energies, the performance of a wide selection of density functional theory (DFT) exchange–correlation functionals, including the latest from the Truhlar and Head-Gordon groups, is evaluated. It was found, using the def2-TZVPP basis set, that the ωB97M-V (MAD 1.8 kcal/mol), ωB97X-V (MAD 2.1 kcal/mol) and SCAN0 (MAD 2.1 kcal/mol) hybrid functionals are recommended. The double-hybrid functionals PWPB95 (MAD 1.6 kcal/mol) and B2K-PLYP (MAD 1.8 kcal/mol) did perform slightly better but this has to be balanced by their increased computational cost.

scholarly journals SVECV-F12: A Composite Scheme for an Accurate and Cost Effective Evaluation of Reaction Barriers. I. Benchmarking Using the HTBH38/08 and NHTBH38/08 Barrier Heights Databases

2020 ◽  
Author(s):  
Oscar Ventura
Keyword(s):  
Density Functional ◽  
Cost Effective ◽  
Basis Set ◽  
Barrier Heights ◽  
Composite Methods ◽  
Complete Basis Set ◽  
Complete Basis Set Limit ◽  
Complete Set ◽  
Reaction Barriers ◽  
Better Than

A simple version of a composite scheme is described, based on a combination of density functional geometry and frequencies evaluation, valence energies obtained using the CCSD(T)-f12 method extrapolated to the complete basis set limit, and core-valence correlation corrections employing the MP2 method. The procedure was applied to the 38 reactions in Truhlar’s HTBH38/08 and NHTBH38/08 databases. Mean unsigned deviation (MUD) for the complete set of 68 independent barriers is 0.43 kcal mol-1, compared to 1.37 kcal/mol for G4 and 1.69 kcal/mol for the dispersioncorrected M06-2X method. Its accuracy is also better that that of other calculations using composite methods of similar cost. The MUD of the new scheme on the barriers in the DBH24/08 subset (12 out of the 38 reactions in both other sets) is 0.31 kcal mol-1, better than that obtained at the expensive CCSD(T,full)/aug-cc-pCV(T+d)Z level (0.46 kcal mol-1) and comparable to the most exact (and costly) Wn calculations (MUD=0.14 kcal mol-1). The maximum unsigned deviation (MaxUD) of the new method for all the reactions studied is 1.71 kcal/mol. G4 and M06-2X, on the other side, exhibit MaxUDs of 6.7 and 8.4 kcal/mol respectively

Evaluating Transition Metal Barrier Heights with the Latest DFT Exchange–Correlation Functionals – the MOBH35 Benchmark Dataset

2019 ◽  
Author(s):  
Mark Iron ◽  
Trevor Janes
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Computational Cost ◽  
Basis Set ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Barrier Heights ◽  
Complete Basis Set ◽  
Complete Basis Set Limit ◽  
Hybrid Functionals

A new database of transition metal reaction barrier heights – MOBH35 – is presented. Benchmark energies (forward and reverse barriers and reaction energy) are calculated using DLPNO-CCSD(T) extrapolated to the complete basis set limit using a Weizmann1-like scheme. Using these benchmark energies, the performance of a wide selection of density functional theory (DFT) exchange–correlation functionals, including the latest from the Truhlar and Head-Gordon groups, is evaluated. It was found, using the def2-TZVPP basis set, that the ωB97M-V (MAD 1.8 kcal/mol), ωB97X-V (MAD 2.1 kcal/mol) and SCAN0 (MAD 2.1 kcal/mol) hybrid functionals are recommended. The double-hybrid functionals PWPB95 (MAD 1.6 kcal/mol) and B2K-PLYP (MAD 1.8 kcal/mol) did perform slightly better but this has to be balanced by their increased computational cost.

scholarly journals SVECV-F12: A Composite Scheme for an Accurate and Cost Effective Evaluation of Reaction Barriers. I. Benchmarking Using the HTBH38/08 and NHTBH38/08 Barrier Heights Databases

2020 ◽  
Author(s):  
Oscar Ventura
Keyword(s):  
Density Functional ◽  
Cost Effective ◽  
Basis Set ◽  
Barrier Heights ◽  
Composite Methods ◽  
Complete Basis Set ◽  
Complete Basis Set Limit ◽  
Complete Set ◽  
Reaction Barriers ◽  
Better Than

A simple version of a composite scheme is described, based on a combination of density functional geometry and frequencies evaluation, valence energies obtained using the CCSD(T)-f12 method extrapolated to the complete basis set limit, and core-valence correlation corrections employing the MP2 method. The procedure was applied to the 38 reactions in Truhlar’s HTBH38/08 and NHTBH38/08 databases. Mean unsigned deviation (MUD) for the complete set of 68 independent barriers is 0.43 kcal mol-1, compared to 1.37 kcal/mol for G4 and 1.69 kcal/mol for the dispersioncorrected M06-2X method. Its accuracy is also better that that of other calculations using composite methods of similar cost. The MUD of the new scheme on the barriers in the DBH24/08 subset (12 out of the 38 reactions in both other sets) is 0.31 kcal mol-1, better than that obtained at the expensive CCSD(T,full)/aug-cc-pCV(T+d)Z level (0.46 kcal mol-1) and comparable to the most exact (and costly) Wn calculations (MUD=0.14 kcal mol-1). The maximum unsigned deviation (MaxUD) of the new method for all the reactions studied is 1.71 kcal/mol. G4 and M06-2X, on the other side, exhibit MaxUDs of 6.7 and 8.4 kcal/mol respectively

scholarly journals SVECV-f12: benchmark of a composite scheme for accurate and cost effective evaluation of reaction barriers.

2021 ◽  
Author(s):  
Oscar Ventura ◽  
Martina Kieninger ◽  
Aline Katz ◽  
Mauricio Vega-Teijido ◽  
Marc E. Segovia ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Density Functional ◽  
Cost Effective ◽  
The Other ◽  
Basis Set ◽  
Barrier Heights ◽  
Composite Methods ◽  
Complete Basis Set ◽  
Complete Basis Set Limit ◽  
Reaction Barriers

A simple composite scheme is presented, based on a combination of density functional geometry and frequencies evaluation, valence energies obtained using the CCSD(T)-f12 method extrapolated to the complete basis set limit, and core-valence correlation corrections employing the MP2 method. The procedure was applied to the 38 reactions in Truhlar’s HTBH38/08 and NHTBH38/08 databases and the errors in the barriers with respect to their best values are presented. Mean unsigned deviation (MUD) for the complete set of 68 independent barriers is 0.40 kcal mol-1 , compared to 1.31 kcal/mol for G4 and 1.62 kcal/mol for the dispersion-corrected M06- 2X method. The accuracy of the procedure is also better that that of other calculations using composite methods of similar cost. The MUD of the new scheme on the barriers in the DBH24/08 subset (12 out of the 38 reactions in the other two sets) is 0.27 kcal mol-1 , better than that obtained at the expensive CCSD(T,full)/aug-cc-pCV(T+d)Z level (0.46 kcal mol-1 ) and comparable to the 2 most exact (and costly) Wn calculations (MUD=0.14 kcal mol-1 ). The maximum unsigned deviation (MaxUD) for all the reactions studied is 0.99 kcal/mol. G4 and M06-2X, on the other side, exhibit MaxUDs of 6.7 and 8.0 kcal/mol respectively. The method was further tested against a subset of the reactions in the databases, for which the geometry and energies of all species were determined at the much more demanding CCSD(T)-F12//pVQZ-F12 level. These results showed that Truhlar’s calculations in this subset are off the best values by a considerable amount, with an rmse of 0.56 kcal/mol. As a consequence, a new dataset of barrier heights, SV20, is presented. The SVECV-F12 procedure on this SV20 database results in rmse and MUD values of only 0.21 and 0.16 kcal/mol. The possible residual errors introduced by the approximations used for each component of the method are tested against more sophisticated calculations and shown to be accurate enough to obtain barriers well under the chemical precision limit at a reasonable cost for molecules of interest in atmospheric chemistry.

scholarly journals Benchmarking quantum mechanical methods for calculating reaction energies of reactions catalyzed by enzymes

2020 ◽  
Vol 2 ◽  
pp. e8 ◽  
Author(s):  
Jitnapa Sirirak ◽  
Narin Lawan ◽  
Marc W. Van der Kamp ◽  
Jeremy N. Harvey ◽  
Adrian J. Mulholland
Keyword(s):  
Density Functional ◽  
Good Choice ◽  
Basis Set ◽  
Basis Sets ◽  
Quantum Mechanical ◽  
Spin Component ◽  
Energy Calculation ◽  
Mp2 Calculations ◽  
Mechanical Methods ◽  
Reaction Energies

To assess the accuracy of different quantum mechanical methods for biochemical modeling, the reaction energies of 20 small model reactions (chosen to represent chemical steps catalyzed by commonly studied enzymes) were calculated. The methods tested included several popular Density Functional Theory (DFT) functionals, second-order Møller Plesset perturbation theory (MP2) and its spin-component scaled variant (SCS-MP2), and coupled cluster singles and doubles and perturbative triples (CCSD(T)). Different basis sets were tested. CCSD(T)/aug-cc-pVTZ results for all 20 reactions were used to benchmark the other methods. It was found that MP2 and SCS-MP2 reaction energy calculation results are similar in quality to CCSD(T) (mean absolute error (MAE) of 1.2 and 1.3 kcal mol−1, respectively). MP2 calculations gave a large error in one case, and are more subject to basis set effects, so in general SCS-MP2 calculations are a good choice when CCSD(T) calculations are not feasible. Results with different DFT functionals were of reasonably good quality (MAEs of 2.5–5.1 kcal mol−1), whereas popular semi-empirical methods (AM1, PM3, SCC-DFTB) gave much larger errors (MAEs of 11.6–14.6 kcal mol−1). These results should be useful in guiding methodological choices and assessing the accuracy of QM/MM calculations on enzyme-catalyzed reactions.

AN EVALUATION OF QUANTUM CHEMICAL CALCULATIONS OF REACTION ENERGIES FOR CATALYTIC ACTIVATION PROCESSES: THE ACTIVATION OF PROPANE BY A RHODIUM CATALYST REVISITED

2012 ◽  
Vol 11 (02) ◽  
pp. 297-312 ◽  
Author(s):  
WILLIAN R. ROCHA ◽  
ÉDER S. XAVIER ◽  
JÚLIO C. S. DA SILVA ◽  
ROBERTA P. DIAS ◽  
HÉLIO F. DOS SANTOS ◽  
...  
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Structural Parameters ◽  
Relative Energy ◽  
Basis Set ◽  
Geometrical Parameters ◽  
Computationally Efficient ◽  
Hartree Fock ◽  
Rhodium Atom ◽  
Reaction Energies

In this paper we report the state of the art CCSD(T)//MP2 ab initio calculations for the activation of propane by cyclopentadienyl carbonyl rhodium, (Cp)Rh(CO) , using the effective core potential of Hay and Wadt (LANL2DZ) for rhodium atom and the correlated consistent polarized valence double-ξ basis set (cc-pVDZ) for C , H and O atoms. The CCSD(T) energy values are used as reference to assess the effect of electron correlation on the reaction energies, as well as the performance of density functional theory (DFT) energy values using various functionals. An investigation on the accuracy of DFT results is relevant since their use in calculations involving large molecular systems is a computationally efficient strategy that enables us to tackle important problems in organometallics field and supramolecular chemistry. Our results for the small model system show that all DFT functionals used here correctly predict the CCSD(T) energy pattern and also reproduce very satisfactorily the MP2 geometrical parameters. The BP86, PBE1PBE and PW91 functionals exhibited the best agreement with structural parameters and relative energy values as compared with ab initio post-Hartree–Fock results, showing a potential use in theoretical investigations on larger systems.

Evaluating Transition Metal Barrier Heights with the Latest DFT Exchange–Correlation Functionals – the MOBH35 Benchmark Dataset

2019 ◽  
Author(s):  
Mark Iron ◽  
Trevor Janes
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Computational Cost ◽  
Basis Set ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Barrier Heights ◽  
Complete Basis Set ◽  
Complete Basis Set Limit ◽  
Hybrid Functionals

A new database of transition metal reaction barrier heights – MOBH35 – is presented. Benchmark energies (forward and reverse barriers and reaction energy) are calculated using DLPNO-CCSD(T) extrapolated to the complete basis set limit using a Weizmann1-like scheme. Using these benchmark energies, the performance of a wide selection of density functional theory (DFT) exchange–correlation functionals, including the latest from the Truhlar and Head-Gordon groups, is evaluated. It was found, using the def2-TZVPP basis set, that the ωB97M-V (MAD 1.8 kcal/mol), ωB97X-V (MAD 2.1 kcal/mol) and SCAN0 (MAD 2.1 kcal/mol) hybrid functionals are recommended. The double-hybrid functionals PWPB95 (MAD 1.6 kcal/mol) and B2K-PLYP (MAD 1.8 kcal/mol) did perform slightly better but this has to be balanced by their increased computational cost.

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