Blar i NTNU Open på forfatter "Folkestad, Sarai Dery"
-
An efficient algorithm for Cholesky decomposition of electron repulsion integrals
Folkestad, Sarai Dery; Kjønstad, Eirik Fadum; Koch, Henrik (Journal article; Peer reviewed, 2019)Approximating the electron repulsion integrals using inner projections is a well-established approach to reduce the computational demands of electronic structure calculations. Here, we present a two-step Cholesky decomposition ... -
Coupled Cluster for High-Spin Open-Shell Systems - A Mixed Orbital Approach
Folkestad, Sarai Dery (Master thesis, 2016)The description of high-spin open-shell systems with coupled cluster (CC) theory presents problems not encountered in the closed-shell case. Spin-contamination and additional computational cost compared to closed-shell ... -
Coupled-Cluster Equation of Motion method (QED-CCSD-1) for Triplet Excitations in Optical Cavities
Smedsrud, Wanjing Huang (Master thesis, 2024)Triplet elektronisk coupled-cluster singles-and-doubles (CCSD) metode med Equation of Motion (EOM) ekspanderes til optiske hull med ett-foton-approksimasjon som triplet EOM QED-CCSD-1 i denne masteroppgaven. Utledningen ... -
Multilevel CC2 and CCSD in Reduced Orbital Spaces: Electronic Excitations in Large Molecular Systems
Folkestad, Sarai Dery; Kjønstad, Eirik Fadum; Goletto, Linda; Koch, Henrik (Peer reviewed; Journal article, 2021)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 lower-level coupled cluster model. To treat ... -
Multilevel CC2 and CCSD Methods with Correlated Natural Transition Orbital
Folkestad, Sarai Dery; Koch, Henrik (Peer reviewed; Journal article, 2019)In the multilevel coupled cluster approach, an active orbital space is treated at a higher level of coupled cluster theory than the remaining inactive orbitals. We introduce the multilevel CC2 method where CC2 is used for ... -
Multilevel coupled cluster methods for large molecular systems
Folkestad, Sarai Dery (Doctoral theses at NTNU;2020:240, Doctoral thesis, 2020)The coupled cluster hierarchy of models can be used to accurately describe electronic excitations in molecular systems. However, the standard coupled cluster models are expensive and their cost severely limits the size of ... -
New Implementation of an Equation-of-Motion Coupled-Cluster Damped-Response Framework with Illustrative Applications to Resonant Inelastic X-ray Scattering
Schnack-Petersen, Anna Kristina; Moitra, Torsha; Folkestad, Sarai Dery; Coriani, Sonia (Journal article; Peer reviewed, 2023)We present an implementation of a damped response framework for calculating resonant inelastic X-ray scattering (RIXS) at the equation-of-motion coupled-cluster singles and doubles (CCSD) and second-order approximate ... -
Predictions of Pre-edge Features in Time-Resolved Near-Edge X-ray Absorption Fine Structure Spectroscopy from Hole–Hole Tamm–Dancoff-Approximated Density Functional Theory
Hohenstein, Edward G; Yu, Jimmy; Bannwarth, Christoph; Holmgaard List, Nanna; Paul, Alexander Christian; Folkestad, Sarai Dery; Koch, Henrik; Martinez, Todd J. (Journal article, 2021)Time-resolved near-edge X-ray absorption fine structure (TR-NEXAFS) spectroscopy is a powerful technique for studying photochemical reaction dynamics with femtosecond time resolution. In order to avoid ambiguity in TR-NEXAFS ... -
Spin-adapted Open-shell Coupled Cluster Theory
Sannes, Bendik Støa (Master thesis, 2022)Åpenskall-molekyler er av stor interesse ettersom de gjennomgående opptrer i kjemi, særlig når det kommer til reaksjonsmekanismer hvor bindinger dannes og brytes. En nøyaktig beskrivelse av slike molekyler er derfor viktig ... -
Transient Resonant Auger-Meitner Spectra of Photoexcited Thymine
Wolf, Thomas J. A.; Paul, Alexander Christian; Folkestad, Sarai Dery; Myhre, Rolf Heilemann; Cryan, James P.; Berrah, Nora; Bucksbaum, Philip H.; Coriani, Sonia; Coslovich, Giacomo; Feifel, Raimund; Martinez, Todd J.; Moeller, Stefan P.; Mucke, Melanie; Obaid, Razib; Plekan, Oksana; Squibb, Richard; Koch, Henrik; Gühr, Markus (Journal article; Peer reviewed, 2021)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 example. Thymine is photoexcited in the UV ... -
Treatment of Large-Scale Systems with Multiscale and Fragmentation Methods
Os, Ylva (Bachelor thesis, 2022)Kvantekjemiske beregning er i dag et stort og viktig felt innen kjemi, og har vært viktigere de siste årene ettersom beregningsteknologien har utviklet seg. Imidlertid er det fortsatt mange utfordringer innenfor dette ...