A5029209831- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Photochemistry and Electron Transfer Studies
- Catalytic Processes in Materials Science
- X-ray Spectroscopy and Fluorescence Analysis
- Molecular spectroscopy and chirality
- Atomic and Molecular Physics
- DNA and Nucleic Acid Chemistry
- 3D Modeling in Geospatial Applications
- Molecular Junctions and Nanostructures
- Advanced NMR Techniques and Applications
- Physics of Superconductivity and Magnetism
- Atmospheric Ozone and Climate
- Inorganic Fluorides and Related Compounds
- Quantum Dots Synthesis And Properties
- Machine Learning in Materials Science
- Quantum, superfluid, helium dynamics
- Atmospheric chemistry and aerosols
- Electron Spin Resonance Studies
- Nonlinear Optical Materials Research
- Photoreceptor and optogenetics research
- Advanced X-ray Imaging Techniques
- Advanced Electron Microscopy Techniques and Applications
- Advanced Physical and Chemical Molecular Interactions
- Mass Spectrometry Techniques and Applications
Norwegian University of Science and Technology
2013-2022
Trondheim Kommune
2020
University of Oslo
2017-2019
Stanford University
2014-2018
SLAC National Accelerator Laboratory
2016-2017
Parc Científic de la Universitat de València
2014
Dalton is a powerful general-purpose program system for the study of molecular electronic structure at Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, Møller-Plesset, configuration-interaction, and coupled-cluster levels theory. Apart from total energy, wide variety properties may be calculated using these electronic-structure models. Molecular gradients Hessians are available geometry optimizations, dynamics, vibrational studies, whereas magnetic resonance optical...
Organic chromophores with heteroatoms possess an important excited state relaxation channel from optically allowed {\pi}{\pi}* to a dark n{\pi}*state. We exploit the element and site specificity of soft x-ray absorption spectroscopy selectively follow electronic change during {\pi}{\pi}*/n{\pi}* internal conversion. As hole forms in n orbital conversion, near edge fine structure (NEXAFS) spectrum at heteroatom K-edge exhibits additional resonance. demonstrate concept nucleobase thymine,...
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 excited singlet states, as well equation motion oscillator strengths, for CCS, CC2, CCSD, CC3. Furthermore, provides unique capabilities such Hartree–Fock real-time propagation CCS CC3 strengths. With a code based Cholesky decomposition algorithm the repulsion integrals, has similar advantages codes using density...
We present a new and efficient implementation of the closed shell coupled cluster singles doubles with perturbative triples method (CC3) in electronic structure program eT. Asymptotically, ground state calculation has an iterative cost 4nV4nO3 floating point operations (FLOP), where nV nO are number virtual occupied orbitals, respectively. The Jacobian transpose transformations, required to iteratively solve for excitation energies transition moments, both require 8nV4nO3 FLOP. have also...
We present a general formalism where different levels of coupled cluster theory can be applied to parts the molecular system. The system is partitioned into subsystems by Cholesky decomposition one-electron Hartree-Fock density matrix. In this way divided across chemical bonds without discontinuities arising. wave function defined in terms operators for each part and these are determined from set equations. total fulfills Pauli-principle all borders electron correlation. develop associated...
We present an efficient implementation of the closed shell multilevel coupled cluster method where singles and doubles (CCSD) is used for inactive orbital space CCSD with perturbative triples (CC3) employed smaller active space. Using Cholesky orbitals, can be spatially localized computational cost greatly reduced compared to full CC3 while retaining accuracy excitation energies. For small organic molecules considered we achieve up two orders magnitude reduction in requirements.
Core excited states are challenging to calculate, mainly because they embedded in a manifold of high-energy valence-excited states. However, their locality makes determination ideal for local correlation methods. In this paper, we demonstrate the performance multilevel coupled cluster theory computing core spectra both within core–valence separated and asymmetric Lanczos implementations linear response theory. We also propose visualization tool analyze excitations using difference between...
In this article, we present a black-box approach for the selection of orbital spaces when computing core excitation energies in multilevel coupled cluster (MLCC) framework. Information available from lower level theory is used to generate correlated natural transition orbitals (CNTOs) high-level calculation by including both singles and doubles information construction orbitals. The inclusion essential obtain set that all contain physical information, contrast where only small subset virtual...
The high resolution near edge X-ray absorption fine structure spectrum of nitrogen displays the vibrational core-excited states. This makes well suited for assessing accuracy different electronic methods core excitations. We report experimental measurements performed at SOLEIL synchrotron facility. These are compared with theoretical spectra calculated using coupled cluster theory and algebraic diagrammatic construction theory. singles doubles perturbative triples model known as CC3 is shown...
We derive the crossing conditions at conical intersections between electronic states in coupled cluster theory and show that if Jacobian matrix is nondefective, two (three) independent are correctly placed on nuclear degrees of freedom for an inherently real (complex) Hamiltonian. Calculations using a 21A'/31A' intersection hypofluorous acid illustrate nonphysical artifacts associated with defects accidental same-symmetry intersections. In particular, observed seam folded about space correct...
We studied the photoinduced ultrafast relaxation dynamics of nucleobase thymine using gas-phase time-resolved photoelectron spectroscopy. By employing extreme ultraviolet pulses from high harmonic generation for photoionization, we substantially extend our spectral observation window with respect to previous studies. This enables us follow excited state population all way low-lying electronic states including ground state. In thymine, observe optically bright 1ππ* a dark 1nπ* within 80 ± 30...
The coupled cluster models CCSD and CC3 are used to investigate the (core) excited states ionization energies of glycine in gas phase. Excited UV spectral range calculated using a standard linear response, while core-level potentials core–valence separation approximation. temperature dependence from different conformers is also assessed.
We present the first investigation of excited state dynamics by resonant Auger–Meitner spectroscopy (also known as Auger spectroscopy) using nucleobase thymine an example.
We present a size-extensive extension to the CC2 model that avoids complications with quasi-degeneracies are in and related perturbation theory-based approaches. The formulation also provides consistent for treating different parts of molecular system at levels electron correlation. Such subsystem approach leads large reductions computational requirements without compromising accuracy. In this initial study, we focus on static properties.
Coupled cluster (CC) methods are among the most accurate in quantum chemistry. However, standard CC linear response formulation is not gauge invariant, resulting errors when modelling properties like optical rotation and electron circular dichroism. Including an explicit unitary orbital Lagrangian makes function but models equivalent to full configuration interaction (FCI) untruncated limit. In this contribution, such briefly discussed it demonstrated that using a nonorthogonal...
We present an efficient implementation of the equation motion oscillator strengths for closed-shell multilevel coupled cluster singles and doubles with perturbative triples method (MLCC3) in electronic structure program eT. The orbital space is split into active part treated CC3 inactive computed at (CCSD) level theory. Asymptotically, contribution scales as O(nVnv3no3) floating-point operations, where nV total number virtual orbitals while nv no are occupied orbitals, respectively....
Abstract In this article, we use two extensively studied systems, a retinal model system and azobenzene, to explore the of coupled cluster models for describing ground singlet excited state potential energy surfaces photoswitchable systems. While not being suitable nuclear dynamics photoisomerization, have useful attributes, such as inclusion dynamical correlation, their black box nature, systematic improvement offered by truncation level. Results systems show that when triple excitations...
We present results from time-resolved NEXAFS spectroscopy at the oxygen edge, which show an extremely high sensitivity on ππ* to nπ* internal conversion. Application thymine clarifies current picture of its photoprotection mechanism.
Summary form only given. Molecules selectively transform light energy from the sun into other forms of like heat, electricity, or chemical with high quantum efficiency. The conversion process is result a correlated motion electrons and nuclei after photoexcitation, often under breakdown Born-Oppenheimer approximation. element site selectivity x-rays allows observing molecular processes different point view compared to ultrafast optical probes [1,2]. I will concentrate on time resolved x-ray...
We present a new and efficient implementation of the closed shell coupled cluster singles doubles with perturbative triples method (CC3) in electronic structure program $e^T$. Asymptotically, ground state calculation has an iterative cost $4n_{\text{V}}^{4}n_{\text{O}}^{3}$ floating point operations (FLOP), where $n_{\text{V}}$ $n_{\text{O}}$ are number virtual occupied orbitals respectively. The Jacobian transpose transformations, required to iteratively solve for excitation energies...