Author
Rolf H. Myhre
Other affiliations: University of Oslo, SLAC National Accelerator Laboratory, Stanford University
Bio: Rolf H. Myhre is an academic researcher from Norwegian University of Science and Technology. The author has contributed to research in topics: Coupled cluster & Excited state. The author has an hindex of 12, co-authored 28 publications receiving 1595 citations. Previous affiliations of Rolf H. Myhre include University of Oslo & SLAC National Accelerator Laboratory.
Papers
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Vilnius University1, University of Ferrara2, Aarhus University3, University of Oslo4, Royal Institute of Technology5, Electromagnetic Geoservices6, University of Trieste7, Norwegian Computing Center8, University of Southern Denmark9, University of Santiago de Compostela10, Danske Bank11, Ruhr University Bochum12, Norwegian Meteorological Institute13, Norwegian Defence Research Establishment14, University of Auckland15, Norwegian University of Science and Technology16, Information Technology University17, Technical University of Ostrava18, Linköping University19, Karlsruhe Institute of Technology20, ETH Zurich21, Australian National University22, University of Modena and Reggio Emilia23, Cisco Systems, Inc.24, University of Buenos Aires25, University of Copenhagen26, University of Erlangen-Nuremberg27, Kazimierz Wielki University in Bydgoszcz28, National Scientific and Technical Research Council29, University of Valencia30, Paul Sabatier University31, University of Melbourne32, University of Nottingham33, University of Bristol34, CLC bio35, Princeton University36, La Trobe University37, Clemson University38
TL;DR: Dalton is a powerful general‐purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational self‐consistent‐field, Møller–Plesset, configuration‐interaction, and coupled‐cluster levels of theory.
Abstract: Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, MOller-Plesset, confi ...
1,212 citations
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SLAC National Accelerator Laboratory1, Norwegian University of Science and Technology2, University of Trieste3, Technical University of Denmark4, University of Gothenburg5, University of Connecticut6, Argonne National Laboratory7, Northwestern University8, Stanford University9, École Polytechnique10, Uppsala University11, Elettra Sincrotrone Trieste12, University of Potsdam13
TL;DR: In this paper, the authors exploit the element and site selectivity of soft X-ray absorption to sensitively follow the ultrafast ππ*/nπ* electronic relaxation of hetero-organic molecules.
Abstract: Many photoinduced processes including photosynthesis and human vision happen in organic molecules and involve coupled femtosecond dynamics of nuclei and electrons Organic molecules with heteroatoms often possess an important excited-state relaxation channel from an optically allowed ππ* to a dark nπ* state The ππ*/nπ* internal conversion is difficult to investigate, as most spectroscopic methods are not exclusively sensitive to changes in the excited-state electronic structure Here, we report achieving the required sensitivity by exploiting the element and site specificity of near-edge soft X-ray absorption spectroscopy As a hole forms in the n orbital during ππ*/nπ* internal conversion, the absorption spectrum at the heteroatom K-edge exhibits an additional resonance We demonstrate the concept using the nucleobase thymine at the oxygen K-edge, and unambiguously show that ππ*/nπ* internal conversion takes place within (60 ± 30) fs High-level-coupled cluster calculations confirm the method’s impressive electronic structure sensitivity for excited-state investigations Many photo-induced processes such as photosynthesis occur in organic molecules, but their femtosecond excited-state dynamics are difficult to track Here, the authors exploit the element and site selectivity of soft X-ray absorption to sensitively follow the ultrafast ππ*/nπ* electronic relaxation of hetero-organic molecules
133 citations
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TL;DR: In this paper, the authors exploit the element and site specificity of soft x-ray absorption spectroscopy to selectively follow the electronic change during the n π/n π* internal conversion.
Abstract: Organic chromophores with heteroatoms possess an important excited state relaxation channel from an optically allowed {\pi}{\pi}* to a dark n{\pi}*state. We exploit the element and site specificity of soft x-ray absorption spectroscopy to selectively follow the electronic change during the {\pi}{\pi}*/n{\pi}* internal conversion. As a hole forms in the n orbital during {\pi}{\pi}*/n{\pi}* internal conversion, the near edge x-ray absorption fine structure (NEXAFS) spectrum at the heteroatom K-edge exhibits an additional resonance. We demonstrate the concept with the nucleobase thymine, a prototypical heteroatomic chromophore. With the help of time resolved NEXAFS spectroscopy at the oxygen K-edge, we unambiguously show that {\pi}{\pi}*/n{\pi}* internal conversion takes place within (60 \pm 30) fs. High-level coupled cluster calculations on the isolated molecules used in the experiment confirm the superb electronic structure sensitivity of this new method for excited state investigations.
96 citations
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TL;DR: The eT program as discussed by the authors is an open source electronic structure package with emphasis on coupled cluster and multilevel methods, including efficient spin adapted implementations of ground and excited singlet states, as well as equation of motion oscillator strengths.
Abstract: 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 and excited singlet states, as well as equation of motion oscillator strengths, for CCS, CC2, CCSD, and CC3. Furthermore, eT provides unique capabilities such as multilevel Hartree-Fock and multilevel CC2, real-time propagation for CCS and CCSD, and efficient CC3 oscillator strengths. With a coupled cluster code based on an efficient Cholesky decomposition algorithm for the electronic repulsion integrals, eT has similar advantages as codes using density fitting, but with strict error control. Here, we present the main features of the program and demonstrate its performance through example calculations. Because of its availability, performance, and unique capabilities, we expect eT to become a valuable resource to the electronic structure community.
66 citations
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TL;DR: A general formalism where different levels of coupled cluster theory can be applied to different parts of the molecular system, which fulfills the Pauli-principle across all borders and levels of electron correlation.
Abstract: We present a general formalism where different levels of coupled cluster theory can be applied to different parts of the molecular system. The system is partitioned into subsystems by Cholesky decomposition of the one-electron Hartree-Fock density matrix. In this way the system can be divided across chemical bonds without discontinuities arising. The coupled cluster wave function is defined in terms of cluster operators for each part and these are determined from a set of coupled equations. The total wave function fulfills the Pauli-principle across all borders and levels of electron correlation. We develop the associated response theory for this multi-level coupled cluster theory and present proof of principle applications. The formalism is an essential tool in order to obtain size-intensive complexity in the calculation of local molecular properties.
53 citations
Cited by
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28,685 citations
01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg
1,652 citations
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TL;DR: Near-infrared-emissive polymer-carbon nanodots possess two-photon fluorescence; in vivo bioimaging and red-light-emitting diodes based on these PCNDs are demonstrated.
Abstract: Near-infrared-emissive polymer-carbon nanodots (PCNDs) are fabricated by a newly developed facile, high-output strategy. The PCNDs emit at a wavelength of 710 nm with a quantum yield of 26.28%, which is promising for deep biological imaging and luminescent devices. Moreover, the PCNDs possess two-photon fluorescence; in vivo bioimaging and red-light-emitting diodes based on these PCNDs are demonstrated.
620 citations
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Uppsala University1, Max Planck Society2, University of Ferrara3, University of Geneva4, State University of New York System5, University of Minnesota6, University of Rostock7, Katholieke Universiteit Leuven8, Lund University9, Stockholm University10, Harvard University11, Interdisciplinary Center for Scientific Computing12, ETH Zurich13, University of Alcalá14, University of Valencia15, University College London16, University of Vienna17, Imperial College London18, Heidelberg University19, Massey University20, University of Strasbourg21, Bowling Green State University22, University of Siena23, Loughborough University24, Hebrew University of Jerusalem25, National University of Singapore26
TL;DR: The OpenMolcas environment is described and features unique to simulations of spectroscopic and magnetic phenomena such as the exact semiclassical description of the interaction between light and matter, various X-ray processes, magnetic circular dichroism and properties are described.
Abstract: In this Article we describe the OpenMolcas environment and invite the computational chemistry community to collaborate. The open-source project already includes a large number of new developments realized during the transition from the commercial MOLCAS product to the open-source platform. The paper initially describes the technical details of the new software development platform. This is followed by brief presentations of many new methods, implementations, and features of the OpenMolcas program suite. These developments include novel wave function methods such as stochastic complete active space self-consistent field, density matrix renormalization group (DMRG) methods, and hybrid multiconfigurational wave function and density functional theory models. Some of these implementations include an array of additional options and functionalities. The paper proceeds and describes developments related to explorations of potential energy surfaces. Here we present methods for the optimization of conical intersections, the simulation of adiabatic and nonadiabatic molecular dynamics, and interfaces to tools for semiclassical and quantum mechanical nuclear dynamics. Furthermore, the Article describes features unique to simulations of spectroscopic and magnetic phenomena such as the exact semiclassical description of the interaction between light and matter, various X-ray processes, magnetic circular dichroism, and properties. Finally, the paper describes a number of built-in and add-on features to support the OpenMolcas platform with postcalculation analysis and visualization, a multiscale simulation option using frozen-density embedding theory, and new electronic and muonic basis sets.
559 citations
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TL;DR: The theory and fundamental principles of the spin-vibronic mechanism for ISC are presented, followed by empirical rules to estimate the rate of ISC within this regime.
Abstract: Intersystem crossing (ISC), formally forbidden within nonrelativistic quantum theory, is the mechanism by which a molecule changes its spin state. It plays an important role in the excited state decay dynamics of many molecular systems and not just those containing heavy elements. In the simplest case, ISC is driven by direct spin–orbit coupling between two states of different multiplicities. This coupling is usually assumed to remain unchanged by vibrational motion. It is also often presumed that spin-allowed radiationless transitions, i.e. internal conversion, and the nonadiabatic coupling that drives them, can be considered separately from ISC and spin–orbit coupling owing to the vastly different time scales upon which these processes are assumed to occur. However, these assumptions are too restrictive. Indeed, the strong mixing brought about by the simultaneous presence of nonadiabatic and spin–orbit coupling means that often the spin, electronic, and vibrational dynamics cannot be described independe...
505 citations