208 citations · 1.4k across the 34 of their papers we have counts for
13 papers · 1 filter
Combining Multilevel Hartree Fock and Multilevel Coupled Cluster with Molecular Mechanics: a Study of Electronic Excitations in Solutions
Linda Goletto, Tommaso Giovannini, Sarai D. Folkestad +1
We investigate the coupling of different quantum-embedding approaches with a third molecular-mechanics layer, which can be either polarizable or non-polarizable. In particular, suc…
Intermolecular interactions in optical cavities: an ab initio QED study
Tor S. Haugland, Christian Schäfer, Enrico Ronca +2
Intermolecular bonds are weak compared to covalent bonds, but they are strong enough to influence the properties of large molecular systems. In this work, we investigate how strong…
Transient Resonant Auger-Meitner Spectra of Photoexcited Thymine
Thomas J. A. Wolf, Alexander C. Paul, Sarai D. Folkestad +15
We present the first investigation of excited state dynamics by resonant Auger-Meitner spectroscopy (also known as resonant Auger spectroscopy) using the nucleobase thymine as an e…
Multilevel Density Functional Theory
Gioia Marrazzini, Tommaso Giovannini, Marco Scavino +3
We introduce a novel density-based multilevel approach in density functional theory. In this multilevel density functional theory (MLDFT), the system is partitioned in an active an…
Energy-Based Molecular Orbital Localization in a Specific Spatial Region
Tommaso Giovannini, Henrik Koch
We present a novel energy-based localization procedure able to localize molecular orbitals into specific spatial regions. The method is applied to several cases including both conj…
A biorthonormal formalism for nonadiabatic coupled cluster dynamics
Eirik F. Kjønstad, Henrik Koch
In coupled cluster methods, the electronic states are biorthonormal in the sense that the left states are orthonormal to the right states. Here we present an extension of this form…
Equation-of-motion MLCCSD and CCSD-in-HF oscillator strengths and their application to core excitations
Sarai D. Folkestad, Henrik Koch
We present an implementation of equation-of-motion oscillator strengths for the multilevel CCSD (MLCCSD) model where CCS is used as the lower level method (CCS/CCSD). In this model…
A new and efficient implementation of CC3
Alexander C. Paul, Rolf H. Myhre, Henrik Koch
We present a new and efficient implementation of the closed shell coupled cluster singles and doubles with perturbative triples method (CC3) in the electronic structure program $e^…
Multilevel CC2 and CCSD in reduced orbital spaces: electronic excitations in large molecular systems
Sarai D. Folkestad, Eirik F. Kjønstad, Linda Goletto +1
We present efficient implementations of the multilevel CC2 (MLCC2) and multilevel CCSD (MLCCSD) models. As the system size increases, MLCC2 and MLCCSD exhibit the scaling of the lo…
Time-dependent coupled cluster theory for ultrafast transient absorption spectroscopy
Andreas S. Skeidsvoll, Alice Balbi, Henrik Koch
We present a spin-adapted time-dependent coupled cluster singles and doubles model for the molecular response to a sequence of ultrashort laser pulses. The implementation is used t…
Coupled Cluster Theory for Molecular Polaritons: Changing Ground and Excited States
Tor S. Haugland, Enrico Ronca, Eirik F. Kjønstad +2
We present an ab initio correlated approach to study molecules that interact strongly with quantum fields in an optical cavity. Quantum electrodynamics coupled cluster theory provi…
Accelerated multimodel Newton-type algorithms for faster convergence of ground and excited state coupled cluster equations
Eirik F. Kjønstad, Sarai D. Folkestad, Henrik Koch
We introduce a multimodel approach to solve coupled cluster equations, employing a quasi Newton algorithm for the ground state and an Olsen algorithm for the excited states. In the…
eT 1.0: an open source electronic structure program with emphasis on coupled cluster and multilevel methods
Sarai D. Folkestad, Eirik F. Kjønstad, Rolf H. Myhre +14
The eT program is an open source electronic structure package with emphasis on coupled cluster and multilevel methods. It includes efficient spin adapted implementations of ground…