W3 theory: robust computational thermochemistry in the kJ/mol accuracy range

Abstract

We are proposing a new computational thermochemistry protocol denoted W3 theory, as a successor to W1 and W2 theory proposed earlier [Martin and De Oliveira, J. Chem. Phys. 111, 1843 (1999)]. The new method is both more accurate overall (error statistics for total atomization energies approximately cut in half) and more robust (particularly towards systems exhibiting significant nondynamical correlation) than W2 theory. The cardinal improvement rests in an approximate account for post-CCSD(T) correlation effects. Iterative T_3 (connected triple excitations) effects exhibit a basis set convergence behavior similar to the T_3 contribution overall. They almost universally decrease molecular binding energies. Their inclusion in isolation yields less accurate results than CCSD(T) nearly across the board: it is only when T_4 (connected quadruple excitations) effects are included that superior performance is achieved. $T_4$ effects systematically increase molecular binding energies. Their basis set convergence is quite rapid, and even CCSDTQ/cc-pVDZ scaled by an empirical factor of 1.2532 will yield a quite passable quadruples contribution. The effect of still higher-order excitations was gauged for a subset of molecules (notably the eight-valence electron systems): T_5 (connected quintuple excitations) contributions reach 0.3 kcal/mol for the pathologically multireference X ^1Σ^+_g state of C_2 but are quite small for other systems. A variety of avenues for achieving accuracy beyond that of W3 theory were explored, to no significant avail. W3 thus appears to represent a good compromise between accuracy and computational cost for those seeking a robust method for computational thermochemistry in the kJ/mol accuracy range on small systems.

J. Chem. Phys., in press (306406JCP)

References in corpus (5)

• Towards standard methods for benchmark quality ab initio thermochemistry --- W1 and W2 theory
• Assessment of W1 and W2 theories for the computation of electron affinities, ionization potentials, heats of formation, and proton affinities
• Electron affinities of the first- and second- row atoms: benchmark ab initio and density functional calculations
• The heat of atomization of sulfur trioxide, SO${}_3$ - a benchmark for computational thermochemistry
• A definitive heat of vaporization of silicon through benchmark ab initio calculations on SiF_4

Cited by in corpus (34)

• Development of Novel Density Functionals for Thermochemical Kinetics
• W4 theory for computational thermochemistry: in pursuit of confident sub-kJ/mol predictions
• Comment on: "Estimating the Hartree-Fock limit from finite basis set calculations" [Jensen F (2005) Theor Chem Acc 113:267]
• Basis set convergence of post-CCSD contributions to molecular atomization energies
• Toward a W4-F12 approach: Can explicitly correlated and orbital-based ab initio CCSD(T) limits be reconciled?
• Assessment of Various Density Functionals and Basis Sets for the Calculation of Molecular Anharmonic Force Fields
• The MOBH35 metal-organic barrier heights reconsidered: performance of local-orbital coupled cluster approaches in different static correlation regimes
• Anharmonic force fields and thermodynamic functions using density functional theory
• Heats of formation of perchloric acid, HClO${}_4$, and perchloric anhydride, Cl${}_2$O${}_7$. Probing the limits of W1 and W2 theory
• Atomization energies of the carbon clusters Cn (n=2--10) revisited by means of W4 theory as well as density functional, Gn, and CBS methods
• Error Assessment of Computational Models in Chemistry
• The lowest singlet-triplet excitation energy of BN: a converged coupled cluster perspective
• Meta-analysis of Uniform Scaling Factors for Harmonic Frequency Calculations
• Molecule-specific Uncertainty Quantification in Quantum Chemical Studies
• Electron Correlation: Nature's Weird and Wonderful Chemical Glue
• W4$\Lambda$: leveraging $\Lambda$ coupled cluster for accurate computational thermochemistry approaches
• When gold is not enough: platinum standard of quantum chemistry with $N^7$ cost
• Analytic Gradients of Approximate Coupled Cluster Methods with Quadruple Excitations
• Another Angle on Benchmarking Noncovalent Interactions
• A static quantum embedding scheme based on coupled cluster theory
• Post-CCSD(T) corrections in the S66 noncovalent interactions benchmark
• Assessment of the accuracy of coupled cluster perturbation theory for open-shell systems. II. Quadruples expansions
• An Exchange-Based Diagnostic for Static Correlation
• Basis set extrapolation from the vanishing counterpoise correction condition
• Accelerating the Convergence of Higher-Order Coupled Cluster Methods II: Coupled Cluster $\Lambda$ Equations and Dynamic Damping
• ZMP-SAPT: DFT-SAPT using ab initio Densities
• Does basis set superposition error significantly affect post-CCSD(T) corrections?
• Resonating Valence Bond Quantum Monte Carlo: Application to the ozone molecule
• Can G4-like Composite Ab Initio Methods Accurately Predict Vibrational Harmonic Frequencies?
• "Best" iterative coupled-cluster triples model: More evidence for 3CC
• Factorized Quadruples and a Predictor of Higher-Level Correlation in Thermochemistry
• Prospects for rank-reduced CCSD(T) in the context of high-accuracy thermochemistry
• Near-exact CCSDT energetics from rank-reduced formalism supplemented by non-iterative corrections
• A new open-shell CCSDTQ implementation and its application to the basis set convergence of post-CCSDT(Q) corrections in computational thermochemistry