Polishing the Gold Standard: The Role of Orbital Choice in CCSD(T) Vibrational Frequency Prediction
Luke W. Bertels, Joonho Lee, Martin Head‐Gordon
Abstract
respectively, outperforming CCSD(T):UHF by nearly a factor of 5. Moreover, the performance on the closed- and open-shell subsets shows these methods are able to treat open-shell and closed-shell systems with comparable accuracy and robustness. CCSD(T) with RHF orbitals is seen to improve upon UHF for the closed-shell species, while spatial symmetry breaking in a number of restricted open-shell HF (ROHF) references leads CCSD(T) with ROHF reference orbitals to exhibit the poorest statistical performance of all methods surveyed for open-shell species. The use of κ-OOMP2 orbitals has also proven useful in diagnosing multireference character that can hinder the reliability of CCSD(T).
Topics & Concepts
Basis setOpen shellSlater-type orbitalAtomic orbitalMolecular orbitalMolecular orbital theoryPhysicsAtomic physicsComplete active spaceChemistryDensity functional theoryLinear combination of atomic orbitalsQuantum mechanicsMoleculeElectronAdvanced Chemical Physics StudiesAdvanced NMR Techniques and ApplicationsMolecular spectroscopy and chirality