W4 theory for computational thermochemistry: In pursuit of confident sub-kJ/mol predictions

Karton, Amir; Rabinovich, É. M.; Martin, Jan M. L.; Ruščić, Branko

doi:10.1063/1.2348881

Cited by 735 publications

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“…In reference 17 we proposed a number of energy-based diagnostics for the importance of nondynamical correlation that are specifically designed for thermochemical purposes. In particular, the %TAE e [(T)] diagnostic, i.e.…”

Section: A Multireference Considerationsmentioning

confidence: 99%

“…It has been shown that highly accurate thermochemical protocols such as HEAT [14][15][16] and W4 17,18 are capable of sub-kJ/mol accuracy on average (see Ref. 19 for a recent review).…”

Section: Introductionmentioning

confidence: 99%

“…17,18 Indeed, the fact that W4 theory and related methods can be carried out at all at a realistic cost hinges on this behavior.…”

Section: Introductionmentioning

confidence: 99%

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Performance of W4 theory for spectroscopic constants and electrical properties of small molecules

Karton

Martin

2010

The Journal of Chemical Physics

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Accurate spectroscopic constants and electrical properties of small molecules are determined by means of W4 and post-W4 theories. For a set of 28 first-and second-row diatomic molecules for which very accurate experimental spectroscopic constants are available, W4 theory affords near-spectroscopic or better predictions. Specifically, the root-mean-square deviations (RMSD) from experiment are 0.04 pm for the equilibrium bond distances (r e ), 1.03 cm −1 for the harmonic frequencies (ω e ), 0.20 cm −1 for the first anharmonicity constants (ω e x e ), 0.10 cm −1 for the second anharmonicity constants (ω e y e ), and 0.001 cm −1 for the vibration-rotation coupling constants (α e ).These RMSD imply 95% confidence intervals of about 0.1 pm for r e , 2.0 cm −1 for ω e , 0.4 cm −1 for ω e x e , and 0.2 cm −1 for ω e y e . We find that post-CCSD(T) contributions are essential to achieve such narrow confidence intervals for r e and ω e , but have little effect on ω e x e and α e , and virtually none on ω e y e . Higher-order connected triples,T 3 −(T), improve agreement with experiment for the hydride systems, but their inclusion (in the absence ofT 4 ) tends to worsen agreement with experiment for the nonhydride systems. Connected quadruple excitations,T 4 , have significant and systematic effects on r e , ω e , and ω e x e , in particular they universally increase r e (by up to 0.5 pm), universally reduce ω e (by up to 32 cm −1 ), and universally increase ω e x e (by up to 1 cm −1 ).Connected quintuple excitations,T 5 , are spectroscopically significant for ω e of the nonhydride systems, affecting ω e by up to 4 cm −1 . Diagonal Born-Oppenheimer corrections have systematic and spectroscopically-significant effects on r e and ω e of the hydride systems, universally increasing r e by 0.01-0.06 pm and decreasing ω e by 0.3-2.1 cm −1 . Obtaining r e and ω e of the pathologically multireference BN and BeO systems with near-spectroscopic accuracy requires large basis sets in the core-valence CCSD(T) step and augmented basis sets in the valence post-CCSD(T) steps in W4 theory. The triatomic molecules H 2 O, CO 2 , and O 3 are also considered. The equilibrium geometries and harmonic frequencies (with the exception of the asymmetric stretch of O 3 ) are obtained with near-spectroscopic accuracy at the W4 level. The asymmetric stretch of ozone represents a severe challenge to W4 theory, in particular the connected quadruple contribution converges very slowly with the basis set size. Finally, the importance of post-CCSD(T) correlation effects for electrical properties, namely dipole moments (µ), polarizabilities (α), and first hyperpolarizabilities (β) is evaluated.2

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Section: A Multireference Considerationsmentioning

confidence: 99%

“…It has been shown that highly accurate thermochemical protocols such as HEAT [14][15][16] and W4 17,18 are capable of sub-kJ/mol accuracy on average (see Ref. 19 for a recent review).…”

Section: Introductionmentioning

confidence: 99%

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Performance of W4 theory for spectroscopic constants and electrical properties of small molecules

Karton

Martin

2010

The Journal of Chemical Physics

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“…[27][28][29] The Wn methods are more sophisticated and computationally expensive, with a typical accuracy of 0.5-1.0 kcal mol -1 . 23,25,26 Well-documented examples where the Gn and Wn families of model chemistries perform unreliably are for systems containing alkali and alkaline earth metal elements. A number of investigations of enthalpies of formation and cation affinities of s-block compounds provides the most egregious deviations for these otherwise successful composite methods.…”

Section: Introductionmentioning

confidence: 99%

Computationals-Block Thermochemistry with the Correlation Consistent Composite Approach

DeYonker

Wilson

et al. 2007

J. Phys. Chem. A

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The correlation consistent composite approach (ccCA) is a model chemistry that has been shown to accurately compute gas-phase enthalpies of formation for alkali and alkaline earth metal oxides and hydroxides (Ho, D. S.; DeYonker, N. J.; Wilson, A. K.; Cundari, T. R. J. Phys. Chem. A 2006, 110, 9767).The ccCA results contrast to more widely used model chemistries where calculated enthalpies of formation for such species can be in error by up to 90 kcal mol -1 . In this study, we have applied ccCA to a more general set of 42 s-block molecules and compared the ccCA ∆H f values to values obtained using the G3 and G3B model chemistries. Included in this training set are water complexes such as Na(H 2 O) n + where n ) 1 -4, dimers and trimers of ionic compounds such as (LiCl) 2 and (LiCl) 3 , and the largest ccCA computation to date: Be-(acac) 2 , BeC 10 H 14 O 4 . Problems with the G3 model chemistries seem to be isolated to metal-oxygen bonded systems and Be-containing systems, as G3 and G3B still perform quite well with a 2.7 and 2.6 kcal mol -1 mean absolute deviation (MAD), respectively, for gas-phase enthalpies of formation. The MAD of the ccCA is only 2.2 kcal mol -1 for enthalpies of formation (∆H f ) for all compounds studied herein. While this MAD is roughly double that found for a ccCA study of >350 main group (i.e., p-block) compounds, it is commensurate with typical experimental uncertainties for s-block complexes. Some molecules where G3/ G3B and ccCA computed ∆H f values deviate significantly from experiment, such as (LiCl) 3 , NaCN, and MgF, are inviting candidates for new experimental and high-level theoretical studies.

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“…21 There are other theories to predict accurate thermochemical data of chemical compounds. The correlation consistent composite approach (ccCA), 22-24 the complete basis set methods (CBS) [25][26][27][28] and the Weizmann theories (Wn), [29][30][31][32] are examples of alternatives to the gaussian-n theories.Theoretical Study of Thermochemical Properties using Composite Methods Adapted to ONIOM J. Braz. Chem.…”

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confidence: 99%

Theoretical study of thermochemical properties using composite methods adapted to ONIOM

Heerdt

Morgon

2012

J. Braz. Chem. Soc.

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Métodos compostos adaptados ao método ONIOM foram utilizados no cálculo teórico de afinidades por próton (PA) e eletrônica (EA) para um grupo de 50 moléculas (álcoois, cetonas, radicais e alcenos). A energia eletrônica foi descrita considerando-se o escalonamento de ZPE (λ) e a correção de alto nível (HLC). O valor ótimo para λ foi obtido através dos dados de PA. Os cálculos de EA foram utilizados na otimização dos termos presentes em HLC. Foram explorados diferentes tipos de funcionais de troca-correlação. A metodologia ONIOM2(QCISD(T)/6-311++G(2dF,p):HF/6-31G(d))//ONIOM2(B3LYP/6-31G(d):HF/6-31G(d)) forneceu os menores desvios absolutos médios para PA e EA, 5,38 kJ mol -1 e 0,11 eV, respectivamente, em comparação com dados experimentais.Composite methods adapted to the ONIOM approach were used in the description of proton (PA) and electron (EA) affinities for a group of 50 molecules (alcohols, ketones, radicals and alkenes). The electronic energy was described considering the scaling ZPE (λ) and higher level (HLC) corrections. The optimal value for λ was obtained from the PA data. The EA calculations were used for optimization of the terms in HLC. Different performances of exchange-correlation functionals were considered. The methodology ONIOM2(QCISD(T)/6-311++G(2dF,p):HF/6-31G(d))//ONIOM2(B3LYP/6-31G(d):HF/6-31G(d)) provided the smallest median absolute deviation (MAD) for PA and EA, 5.38 kJ mol -1 and 0.11 eV, respectively, in comparison to the experimental data.Keywords: proton and electron affinities, composite methods, ONIOM Introduction Molecular modeling calculations using high level (ab initio and DFT methods) and large basis sets have provided determinations of the precise electronic properties of atomic and molecular systems. 1-9 However, practical calculations containing many particles become a task that requires a very high computational cost. 10 Some strategies have been successful, making it possible to study large systems, highlighting the composite methods [11][12][13][14][15][16][17][18][19] and the ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) method. 20 Developed in the 1980s, the composite methods aim to extrapolate the electronic energies from a sequence of calculations, computationally inexpensive, to an electronic energy with a high level of correlation and large basis set. 2 In addition to the energy terms from the energy calculations, some empirical parameters can be added to correct deficiencies of the method, like additional correlation effects, relativistic effect, etc.The Gaussian-n theory, developed by Pople and co-workers, 13-17 exploits this idea to predict thermochemical data of molecules containing elements of the first three periods of the periodic table. The purpose of this theory is to obtain a general procedure that can reproduce experimental data for properties such as proton and electron affinities, ionization energy, enthalpy of formation, etc., being applicable to any molecular system unambiguously. Recently, new approaches of these theo...

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W4 theory for computational thermochemistry: In pursuit of confident sub-kJ/mol predictions

Cited by 735 publications

References 72 publications

Performance of W4 theory for spectroscopic constants and electrical properties of small molecules

Performance of W4 theory for spectroscopic constants and electrical properties of small molecules

Computationals-Block Thermochemistry with the Correlation Consistent Composite Approach

Theoretical study of thermochemical properties using composite methods adapted to ONIOM

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