Elucidating the molecular orbital dependence of the total electronic energy in multireference problems
arXiv:2301.00668 · doi:10.1063/5.0090342
Abstract
The accurate resolution of the chemical properties of strongly correlated systems, such as biradicals, requires the use of electronic structure theories that account for both multi-reference as well as dynamic correlation effects. A variety of methods exist that aim to resolve the dynamic correlation in multi-reference problems, commonly relying on an exponentially scaling complete-active-space self-consistent-field (CASSCF) calculation to generate reference molecular orbitals (MOs). However, while CASSCF orbitals provide the optimal solution for a selected set of correlated (active) orbitals, their suitability in the quest for the resolution of the total correlation energy has not been thoroughly investigated. Recent research has shown the ability of Kohn-Shan density functional theory (KS-DFT) to provide improved orbitals for coupled cluster (CC) and Møller-Plesset perturbation theory (MP) calculations. Here we extend the search for optimal and more cost effective MOs to post-configuration-interaction (post-CI) methods, surveying the ability of the MOs obtained with various DFT functionals, as well as Hartree-Fock, and CC and MP calculations to accurately capture the total electronic correlation energy. Applying the anti-Hermitian contracted Schrödinger equation (ACSE) to the dissociation of N, the calculation of biradical singlet-triplet gaps and the transition states of the bicylobutane isomerization, we demonstrate DFT provides a cost-effective alternative to CASSCF in providing reference orbitals for post-CI dynamic correlation calculations.
References in corpus (12)
- Reduced Density Matrix Functional for Many-Electron Systems
- Designer spin order in diradical nanographenes
- Global Natural Orbital Functional: Towards the Complete Description of the Electron Correlation
- Towards a formal definition of static and dynamic electronic correlations
- Ensemble reduced density matrix functional theory for excited states and hierarchical generalization of Pauli's exclusion principle
- Range-separated multideterminant density-functional theory with a short-range correlation functional of the on-top pair density
- Third order Møller-Plesset theory made more useful? The role of density functional theory orbitals
- Polishing the Gold Standard: The Role of Orbital Choice in CCSD(T) Vibrational Frequency Prediction
- Spin-free formulation of the multireference driven similarity renormalization group: A benchmark study of first-row diatomic molecules and spin-crossover energetics
- Accurate singlet-triplet gaps in biradicals via the spin averaged anti-Hermitian contracted Schrödinger equation
- Machine Learning Universal Bosonic Functionals
- Incremental Treatments of the Full Configuration Interaction Problem