4 papers · 1 filter
The remarkable accuracy of an perturbative correction to opposite-spin CCSD: are triples necessary for chemical accuracy in coupled cluster?
David W. Small
The focus of this work is OS-CCSD-SPT(2), which is a second-order similarity transformed perturbation theory correction to opposite spin coupled cluster singles doubles, where in t…
Excited States via Coupled Cluster Theory without Equation-of-Motion Methods: Seeking Higher Roots with Application to Doubly Excited States and Double Core Hole States
Joonho Lee, David W. Small, Martin Head-Gordon
In this work, we revisited the idea of using the coupled-cluster ground state formalism to target excited states. Our main focus was targeting doubly excited states and double core…
Kohn-Sham Density Functional Theory with Complex, Spin-Restricted Orbitals: Accessing a New Class of Densities without the Symmetry Dilemma
Joonho Lee, Luke W. Bertels, Martin Head-Gordon
We show that using complex, spin-restricted orbitals (cR) in Kohn-Sham density functional theory (KS-DFT) allows one to access a new class of densities that is not accessible by ei…
Open-Shell Coupled-Cluster Valence-Bond Theory Augmented with an Independent Amplitude Approximation for Three-Pair Correlations: Application to a Model Oxygen-Evolving Complex and Single Molecular Magnet
Joonho Lee, David W. Small, Martin Head-Gordon
We report the failure of coupled-cluster valence-bond (CCVB) theory with two-pair configurations [J. Chem. Phys. 2009, 130, 084103 (2009)] for open-shell (OS) spin-frustrated syste…