208 citations · 569 across the 23 of their papers we have counts for
8 papers · 1 filter
Generalized coupled cluster theory for ground and excited state intersections
Federico Rossi, Eirik F. Kjønstad, Sara Angelico +1
Coupled cluster theory in the standard formulation is unable to correctly describe conical intersections among states of the same symmetry. This limitation has restricted the pract…
Determining minimum energy conical intersections by enveloping the seam: exploring ground and excited state intersections in coupled cluster theory
Sara Angelico, Eirik F. Kjønstad, Henrik Koch
Minimum energy conical intersections can be used to rationalize photochemical processes. In this Letter, we examine an algorithm to locate these structures that does not require th…
Understanding failures in electronic structure methods arising from the geometric phase effect
Eirik F. Kjønstad, Henrik Koch
The geometric phase effect arises from the dependence on the nuclear coordinates in the electronic Hamiltonian, leading to sign changes of the electronic wave functions upon traver…
Fermionic tensor network contraction for arbitrary geometries
Yang Gao, Huanchen Zhai, Johnnie Gray +5
We describe our implementation of fermionic tensor network contraction on arbitrary lattices within both a globally ordered and locally ordered formalism. We provide a pedagogical…
Analytical evaluation of ground state gradients in quantum electrodynamics coupled cluster theory
Marcus Takvam Lexander, Sara Angelico, Eirik Fadum Kjønstad +1
Analytical gradients of potential energy surfaces play a central role in quantum chemistry, allowing for molecular geometry optimizations and molecular dynamics simulations. In str…
Unexpected hydrogen dissociation in thymine: predictions from a novel coupled cluster theory
Eirik F. Kjønstad, O. Jonathan Fajen, Alexander C. Paul +6
The fate of thymine upon excitation by ultraviolet radiation has been the subject of intense debate over the past three decades. Today, it is widely believed that its ultrafast exc…
Coupled cluster theory for nonadiabatic dynamics: nuclear gradients and nonadiabatic couplings in similarity constrained coupled cluster theory
Eirik F. Kjønstad, Sara Angelico, Henrik Koch
Coupled cluster theory is one of the most accurate electronic structure methods for predicting ground and excited state chemistry. However, the presence of numerical artifacts at e…
Prediction of Photodynamics of 200 nm Excited Cyclobutanone with Linear Response Electronic Structure and Ab Initio Multiple Spawning
Diptarka Hait, Dean Lahana, O. Jonathan Fajen +6
Simulations of photochemical reaction dynamics have been a challenge to the theoretical chemistry community for some time. In an effort to determine the predictive character of cur…