Cristin-resultat-ID: 2042457
Sist endret: 11. august 2022, 14:01

Coupled-Cluster Theory for Electron Dynamics

  • Håkon Emil Kristiansen



Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Oslo


Series of dissertations submitted to the Faculty of Mathematics and Natural Sciences, University of Oslo.
ISSN 1501-7710
NVI-nivå 0

Om resultatet

Publiseringsår: 2022
Volum: 2022
Hefte: 2507


Fagfelt (NPI)

Fagfelt: Kjemi
- Fagområde: Realfag og teknologi

Beskrivelse Beskrivelse


Coupled-Cluster Theory for Electron Dynamics


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.


Håkon Emil Kristiansen

  • Tilknyttet:
    ved Hylleraas-senteret ved Universitetet i Oslo

Thomas Bondo Pedersen

  • Tilknyttet:
    ved Teoretisk kjemi ved Universitetet i Oslo

Simen Kvaal

  • Tilknyttet:
    ved Teoretisk kjemi ved Universitetet i Oslo
Inaktiv cristin-person

Kenneth Ruud

  • Tilknyttet:
    ved Institutt for kjemi ved UiT Norges arktiske universitet
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