3 papers
physics.chem-ph2026
Symmetry-adapted generalised normal-ordered coupled-cluster theory for excited states
Nicholas Lee, David P. Tew, Bang C. Huynh
Ground and excited electronic states in highly symmetric systems typically possess high degrees of spatial degeneracy as a consequence of point-group symmetry. However, many curren…
physics.chem-ph2025
Spin-free Generalised Normal Ordered Coupled Cluster
Nicholas Lee, David P. Tew
We present a spin-free, size-extensive, and size-consistent coupled cluster method based on a generalised normal ordered exponential ansatz. This approach is a natural generalisati…
physics.chem-ph2024
Multi-reference coupled cluster theory using the normal ordered exponential ansatz
Alexander Gunasekera, Nicholas Lee, David P. Tew
Properly spin-adapted coupled-cluster theory for general open-shell configurations remains an active area of research in electronic structure theory. In this contribution we examin…