The high resolution near edge X-ray absorption fine structure spectrum of nitrogen displays the vibrational structure of the core-excited states. This makes nitrogen well suited for assessing the accuracy of different ...

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 ...

As a part of the ongoing development of the multi level coupled cluster (MLCC) model ECC2, the work presented here is focused on obtaining transition moments associated with certain excitation energies. The ECC2 model ...

Reliably predicting nuclear dynamics in excited electronic states requires an accurate representation of the involved electronic states. One challenge in this respect is the correct description of electronic degeneracies, ...

We derive the crossing conditions at conical intersections between electronic states in coupled cluster theory and show that if the coupled cluster Jacobian matrix is nondefective, two (three) independent conditions are ...

This thesis is part of an ongoing research project into the development and implementation of multi-level coupled cluster (MLCC) theory. In MLCC, the orbital space is divided into two or more subspaces. Based on which ...

We present a novel energy-based localization procedure able to localize molecular orbitals into predefined spatial regions. The method is defined in a multiscale framework based on the multilevel Hartree–Fock approach. In ...

Ferroelectric materials are everywhere in the modern society, from consumer electronics to car engines. Applications cover a whole range of devices such as sensors, actuators and transducers due to their dielectric or ...

I denne avhandlingen introduseres kvanteelektrodynamisk ''coupled cluster'' teori (QED-CC) som en ny og nøyaktig ab initio teori for å undersøke sterk kobling mellom lys og materie i optiske kaviteter. Ligningene for ...

Karbonmaterialer brukes som kledning under produksjonen av primærmetall. Høy temperatur, strøm og et kjemisk tærende miljø sliter materialene under drift. En bidragende årsak til slitasjen er inntrengning av natrium. ...