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Schrader, Simon Elias; Kristiansen, Håkon Emil; Pedersen, Thomas Bondo & Kvaal, Simen
(2023).
Time evolution of the Hydrogen atom in a strong laser field using Rothe's method.
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Schrader, Simon Elias; Kristiansen, Håkon Emil; Pedersen, Thomas Bondo & Kvaal, Simen
(2023).
Time evolution of the Hydrogen atom in a strong laser field using Rothe's method.
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Pedersen, Thomas Bondo
(2023).
Coupled-cluster theory of electron dynamics.
Show summary
Highly accurate simulation of laser-driven electron dynamics is important for the prediction and interpretation of advanced spectroscopic experiments, including electronic response to sub-femtosecond laser pulses, which allow investigation and control of matter at the time scale of the electron. While multi-configurational methods have dominated the field for decades, recent years have witnessed increased interest in single-reference coupled-cluster methods for the simulation of electron dynamics [1]. Time-dependent coupled-cluster methods will be reviewed with emphasis on the major challenges for future developments.
[1] B. S. Ofstad, E. Aurbakken, O. S. Schoyen, H. E. Kristiansen, S. Kvaal, and T. B. Pedersen, "Time-Dependent Coupled-Cluster Theory", WIREs Comput. Mol. Sci. 2023, e1666 (in press; DOI: 10.1002/wcms.1666)
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Pedersen, Thomas Bondo
(2023).
Recent Developments in Time-Dependent Coupled-Cluster Theory.
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Kvaal, Simen; Pedersen, Thomas Bondo; Lasser, Caroline & Adamowicz, Ludwik
(2022).
No need for a grid: Gaussians for the time-dependent Schrödinger equation.
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Kvaal, Simen; Pedersen, Thomas Bondo; Lasser, Caroline & Adamowicz, Ludwik
(2022).
Time evolution using linear combinations of gaussians.
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Pedersen, Thomas Bondo
(2022).
From Electronic Dynamics to Fully Coupled Electronic-Nuclear Dynamics.
Show summary
Molecular control at the time and length scale of the electron is a grand challenge for science, which may be achieved using ultrashort laser pulses down to the attosecond time scale In order to understand and predict phenomena arising from the interaction between laser pulses and matter, we are forced t solve the time-dependent Schr{\"o}dinger equation for both electronic and nuclear degrees of freedom. I will give a brief overview of our recent work on explicitly time-dependent quantum-mechanical methods, both laser-induced electronic dynamics within the Born-Oppenheimer approximation [1-4] and coupled electronic-nuclear dynamics without the Born-Oppenheimer approximation [5]. For the electronic dynamics part, emphasis will be put on the interpretation of time dependent coupled-cluster theory in terms of autocorrelation functions and stationary-state populations, whereas the non-Born-Oppenheimer part will focus on the important phenomenon of laser-induced molecular alignment.
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Hauge, Eirill Strand & Pedersen, Thomas Bondo
(2021).
Extrapolating the electric dipole moment of real-time electronic structure calculations.
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Pedersen, Thomas Bondo
(2021).
Interpretation of Coupled-Cluster Quantum Dynamics.
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Pedersen, Thomas Bondo
(2020).
Laser-Driven Many-Electron Dynamics with Coupled-Cluster Theory.
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Pedersen, Thomas Bondo
(2019).
Can Coupled-Cluster Theory Describe Ultrashort, High-Intensity Laser-Driven Electron Dynamics?
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Pedersen, Thomas Bondo
(2019).
Electron Dynamics in Extreme Laser Pulses: A Challenge to Coupled-Cluster Theory.
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Pedersen, Thomas Bondo & Kvaal, Simen
(2018).
Electron Dynamics with Coupled-Cluster Theory.
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Pedersen, Thomas Bondo & Kvaal, Simen
(2018).
Time-Dependent Coupled-Cluster Theory.
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Baardsen, Gustav; Rebolini, Elisa; Hansen, Audun Skau; Maschio, Lorenzo; Leikanger, Karl Roald & Pedersen, Thomas Bondo
(2018).
The divide-expand-consolidate method for extended systems.
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Pedersen, Thomas Bondo
(2018).
New Directions in Coupled-Cluster Theory.
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Hansen, Audun Skau; Baardsen, Gustav; Maschio, Lorenzo & Pedersen, Thomas Bondo
(2018).
Locality and sparsity in local correlation calculations.
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Rebolini, Elisa; Baardsen, Gustav; Hansen, Audun Skau; Leikanger, Karl Roald & Pedersen, Thomas Bondo
(2018).
Error-controlled MP2 for periodic molecular systems.
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Pedersen, Thomas Bondo
(2017).
Coupled-cluster theory: Quo Vadis?
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Rebolini, Elisa; Baardsen, Gustav; Hansen, Audun Skau; Leikanger, Karl Roald & Pedersen, Thomas Bondo
(2017).
Local coupled cluster methods for periodic systems.
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Pedersen, Thomas Bondo
(2017).
Local Coupled-Cluster Theory with Periodic Boundary Conditions.
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Pedersen, Thomas Bondo
(2017).
Divide-Expand-Consolidate Coupled-Cluster Theory for Extended Systems.
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Pedersen, Thomas Bondo
(2017).
Esoteric or Exoteric? Gauge Invariance, Time Propagation, and Coupled-Cluster Theory.
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Pedersen, Thomas Bondo
(2016).
Local coupled-cluster methods for periodic systems.
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Leikanger, Karl R.; Rebolini, Elisa; Hansen, Audun Skau; Baardsen, Gustav & Pedersen, Thomas Bondo
(2016).
Hartree-Fock calculations using a priori Wannier orbitals for solids.
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Wirz, Lukas Nico; Reine, Simen Sommerfelt; Pedersen, Thomas Bondo & Helgaker, Trygve
(2016).
Efficient auxiliary bases for the non-robust pair atomic resolution of the identity (PARI) method.
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Rebolini, Elisa; Izsak, Robert; Reine, Simen Sommerfelt; Helgaker, Trygve & Pedersen, Thomas Bondo
(2016).
Comparison of three efficient approximate exact-exchange algorithms: chain-of-spheres, pair-atomic resolution of the identity, and the auxiliary density matrix method.
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Galván, Ignacio Fdez.; Delcey, Mickaël G.; Pedersen, Thomas Bondo; Aquilante, Francesco & Lindh, Roland
(2016).
Conical intersection optimization and characterization with density-fitted two-electron integrals.
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Pedersen, Thomas Bondo
(2016).
Coupled cluster methods for periodic systems.
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Pedersen, Thomas Bondo
(2016).
A quantum chemistry approach to condensed phases using periodic boundary conditions.
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Pedersen, Thomas Bondo
(2015).
On the pair atomic resolution of the identity approximation.
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Pedersen, Thomas Bondo
(2015).
On the Pair Atomic Resolution of the Identity Approximation.
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Pedersen, Thomas Bondo
(2014).
Accelerating Quantum Chemistry using Local Density Fitting.
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Pedersen, Thomas Bondo
(2014).
The Random Phase Approximation.
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Pedersen, Thomas Bondo; Rekkedal, Johannes Andreas; Leikanger, Karl R.; Iozzi, Maria Francesca; Coriani, Sonia & Teale, Andrew Michael
(2014).
Molecular Properties in the Random Phase Approximation.
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Pedersen, Thomas Bondo
(2014).
The CD project - a status report.
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Pedersen, Thomas Bondo
(2013).
Cholesky decomposition and density fitting in Molcas.
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Pedersen, Thomas Bondo
(2013).
The Random Phase Approximation.
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Pedersen, Thomas Bondo; Rekkedal, Johannes Andreas; Iozzi, Maria Francesca; Coriani, Sonia; Teale, Andrew Michael & Helgaker, Trygve
(2013).
Molecular Properties in the Random Phase Approximation.
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Kristiansen, Håkon Emil; Pedersen, Thomas Bondo; Kvaal, Simen & Ruud, Kenneth
(2022).
Coupled-Cluster Theory for Electron Dynamics.
Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Oslo.
ISSN 1501-7710.
2022(2507).
Show summary
Coupled-cluster (CC) theory, often referred to as the gold standard of quantum chemistry, defines a convergent hierarchy of increasingly accurate methods for the description of molecular properties. The same hierarchy of methods can be extended to time-dependent electronic structure theory which is then referred to as time-dependent CC theory (TDCC).
TDCC theory can be formulated with static orbitals or with dynamic orbitals. In his thesis, the candidate has developed software implementing both variants. An assessment of the importance of employing dynamic orbitals is given.
A drawback of TDCC theory is the difficulty of interpretation due to the non-Hermitian formulation. For example, there is no fully consistent definition of excited states in CC theory, preventing the calculation of stationary-state populations. Based on equation-of-motion CC (EOMCC) and CC linear response (CCLR) theory, we propose two sets of projection operators that yield time-dependent stationary-state populations as expectation values.
Furthermore, TDCC methods are computationally expensive. To bring reduce the computational cost, approximations to specific orders of the theory can be formulated based on perturbation theory. The candidate has developed a program for a second-order approximation to TDCC theory with dynamic orbitals and applied the method to the description of optical properties in small molecules.
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Hansen, Audun Skau; Pedersen, Thomas Bondo; Helgaker, Trygve & Kvaal, Simen
(2021).
Local correlation methods for infinite systems.
Universitetet i Oslo, Det matematisk-naturvitenskapelige fakultet.
ISSN 1501-7710.
2021(2380).
Full text in Research Archive
Show summary
Quantum Chemistry constitutes an extensive framework for accurately simulating the electronic wavefunction of atoms and molecules. The same framework may in principle be applied to the domain of periodic structures such as crystals, but is in practice severely limited by the infinite nature of these structures in conjunction with the computational complexity of quantum chemical methods. In his thesis, the candidate utilizes a mathematical structure known as bi-infinite block-Toeplitz matrices in order to smoothly transition between the molecular and periodic realm. Furthermore, he extends the divide-expand-consolidate methods originally devised for molecules to the periodic case, and demonstrates that this procedure can reduce the computational scaling of the simulation while retaining systematic control over the error.
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