Dage Sundholm

University of Helsinki

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Rashid R. Valiev

National Research Tomsk State University

Heike Fliegl

FIZ Karlsruhe – Leibniz Institute for Information Infrastructure

Jeppe Olsen

Aarhus University

Maria Dimitrova

University of Helsinki

Pekka Pyykkö

University of Helsinki

Jonas Jusélius

UiT The Arctic University of Norway

Ville R. I. Kaila

Stockholm University

Mikael P. Johansson

University of Helsinki

Olli Lehtonen

University of Eastern Finland

José M. López‐de‐Luzuriaga

Universidad de La Rioja

Cooperative Institutions

University of Helsinki

Centre National de la Recherche Scientifique

Karlsruhe Institute of Technology

National Research Tomsk State University

Helsinki Institute of Physics

University of Oslo

Aarhus University

Robert Bosch (Germany)

KTH Royal Institute of Technology

Johannes Gutenberg University Mainz

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Calculation of vibrationally resolved absorption spectra of acenes and pyrene

Physical Chemistry Chemical Physics (2019)

Isaac Benkyi Enrico Tapavicza Heike Fliegl Dage Sundholm

The absorption spectra of naphthalene, anthracene, pentacene and pyrene in the ultraviolet-visible (UV-Vis) range have been simulated by using an efficient real-time generating function method that combines calculated adiabatic electronic excitation energies with vibrational energies of the excited states. The vertical electronic excitation energies have been calculated at the density functional theory level using the PBE0 functional and at the second-order approximate coupled-cluster level (CC2). The absorption spectra have been calculated at the PBE0 level for the studied molecules and at the CC2 level for naphthalene. The transition probabilities between vibrationally resolved states were calculated by using the real-time generating function method employing the full Duschinsky formalism. The absorption spectrum for naphthalene calculated at the PBE0 and CC2 levels agrees well with the experimental one after the simulated spectra have been blue-shifted by 0.48 eV and 0.12 eV at the PBE0 and CC2 level, respectively. The absorption spectra for anthracene, pentacene and pyrene simulated at the PBE0 level agree well with the experimental ones when they are shifted by 0.49 eV, 0.57 eV and 0.46 eV, respectively. The strongest transitions of the main vibrational bands have been assigned.

Pentacene

10.1039/c9cp04178h

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Citations (56)

Two-dimensional, fully numerical molecular calculations

Molecular Physics (1985)

Dage Sundholm Pekka Pyykkö Leif Laaksonen

Fully numerical two-dimensional Hartree-Fock calculations are reported for the ground states of the diatomic systems He2, Li2, Be2, HF, OH-, N2, CO, BF, NO+ and CN-. total energies, electric multipole moments and electric field gradients are given. A close agreement with the seminumerical results by McCullough is obtained. High multipole moments, up to Q 10, are reported and compared to LCAO ones. The role of correlation in nuclear quadrupole coupling constants is discussed.

Diatomic molecule

Coupling constant

Electric field gradient

10.1080/00268978500103131

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Citations (118)

Luminescent Characterization of Solution Oligomerization Process Mediated Gold−Gold Interactions. DFT Calculations on [Au₂Ag₂R₄L₂]_nMoieties

Journal of the American Chemical Society (2000)

Eduardo J. Fernández M. Concepción Gimeno Antonio Laguna José M. López‐de‐Luzuriaga Miguel Monge

The optical properties of [Au2Ag2(C6F5)4(OCMe2)2]n (1) have been studied in the solid state at room temperature and at 77 K and in acetone solution (5 × 10-4 M). The crystal structure of 1, analyzed by X-ray diffraction, consists of polymeric chains formed by repetition of Au2Ag2 moieties linked through short gold−gold interactions. The emission profile observed for 1 in dilute acetone solution (5 × 10-4 M) is assignable to pentafluorophenyl localized ππ* excited states or from π-MMCT transitions, and in the solid-state arises from metal-centered (dσ*)1(pσ)1 or (dδ*)1(pσ)1 excited states. When the absorption and emission spectra of compound 1 in acetone are registered at different concentrations, they display a band that does not obey the Lambert−Beer law. This deviation is consistent with molecular aggregation in solution through gold−gold interactions, and a clear correlation between the emission wavelength and the structure of 1 in the solid state and in solution is shown. DFT calculations accord with the observed experimental behavior and show the nature of the orbitals involved in each transition.

Crystal (programming language)

10.1021/ja9942540

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Citations (138)

Hydrogen-bond strengths by magnetically induced currents

Physical Chemistry Chemical Physics (2010)

Heike Fliegl Olli Lehtonen Dage Sundholm Ville R. I. Kaila

We present here a "non-invasive" computational method to estimate the strength of individual hydrogen bonds using magnetically induced currents. The method is calibrated using H-bonding dimers, and applied on Watson-Crick DNA base pairs and proton wires in carbonic anhydrase.

10.1039/c0cp00622j

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Magnetically Induced Current-Density Susceptibility of Circum[n]coronenes

The Journal of Physical Chemistry A (2025)

Qian Wang Stefan Taubert Dage Sundholm

We have calculated the magnetically induced current density (MICD) susceptibility at the all-electron density functional theory level for a series of coronoid molecules of increasing size and compared the MICD susceptibilities with those calculated using the pseudo-π (PP) model. The molecules sustain global diatropic magnetically induced ring currents (MIRCs), whereas paratropic MICD vortices mainly appear inside the benzene rings. The computationally cheaper PP calculations were also employed on circum[n]coronene molecules showing that the MICD pattern continues to alternate for odd and even n when increasing the size of the molecule. For even n, there is a local paratropic MIRC in the middle of the molecule, whereas when n is odd, the PP models do not sustain any paratropic MIRC pathways. The global diatropic MIRC flowing mainly along the outer edge of the molecule increases with increasing n suggesting that there is no size limit of the MIRC of circum[n]coronene molecules. There are seven weakly aromatic Clar rings in the middle of the PP model of the circum[n]coronene molecules with odd n, whereas circum[n]coronene molecules with even n have no Clar rings. There are no Clar rings in the outer part of the circum[n]coronene molecules with n > 1.

Coronene

10.1021/acs.jpca.4c07293

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Ab Initio Study of Phosphorescence of Hetero[8]Circulenes

Russian Physics Journal (2019)

Rashid R. Valiev Glib Baryshnikov V. N. Cerepanov Dage Sundholm

10.1007/s11182-019-01727-7

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Aromatic and Antiaromatic Pathways in a Triphyrin(2.1.1) Fused with Benzo[b]heterocycles

Maria Dimitrova Krzysztof Bartkowski Piotr J. Chmielewski Miłosz Pawlicki Dage Sundholm

Antiaromaticity

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Spatial Contributions to Nuclear Magnetic Shieldings

The Journal of Physical Chemistry A (2021)

Rahul Kumar Jinger Heike Fliegl Radovan Bast Maria Dimitrova Susi Lehtola

We develop a methodology for calculating, analyzing, and visualizing nuclear magnetic shielding densities which are calculated from the current density via the Biot–Savart relation. Atomic contributions to nuclear magnetic shielding constants can be estimated within our framework with a Becke partitioning scheme. The new features have been implemented in the GIMIC program and are applied in this work to the study of the 1H and 13C nuclear magnetic shieldings in benzene (C6H6) and cyclobutadiene (C4H4). The new methodology allows a visual inspection of the spatial origins of the positive (shielding) and negative (deshielding) contributions to the nuclear magnetic shielding constant of a single nucleus, something which has not been hitherto easily accomplished. Analysis of the shielding densities shows that diatropic and paratropic current-density fluxes yield both shielding and deshielding contributions, as the shielding or deshielding is determined by the direction of the current-density flux with respect to the studied nucleus instead of the tropicity. Becke partitioning of the magnetic shieldings shows that the magnetic shielding contributions mainly originate from the studied atom and its nearest neighbors, confirming the localized character of nuclear magnetic shieldings.

Cyclobutadiene

10.1021/acs.jpca.0c10884

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Citations (23)

Parallel implementation of a direct method for calculating electrostatic potentials

The Journal of Chemical Physics (2007)

Jonas Jusélius Dage Sundholm

The authors present a method for calculating the electrostatic potential directly in a straightforward manner. While traditional methods for calculating the electrostatic potential usually involve solving the Poisson equation iteratively, the authors obtain the electrostatic interaction potential by performing direct numerical integration of the Coulomb-law expression using finite-element functions defined on a grid. The singularity of the Coulomb operator is circumvented by an integral transformation and the resulting auxiliary integral is obtained using Gaussian quadrature. The three-dimensional finite-element basis is constructed as a tensor (outer) product of one-dimensional functions, yielding a partial factorization of the expressions. The resulting algorithm has, without using any prescreening or other computational tricks, a formal computational scaling of O(N4∕3), where N is the size of the grid. The authors show here how to implement the method for efficiently running on parallel computers. The matrix multiplications of the innermost loops are completely independent, yielding a parallel algorithm with the computational costs scaling practically linearly with the number of processors.

Basis function

Poisson's equation

10.1063/1.2436880

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Citations (28)

Electrostatic spectral tuning mechanism of the green fluorescent protein

Physical Chemistry Chemical Physics (2013)

Ville R. I. Kaila Robert Send Dage Sundholm

Understanding the mechanism of spectral tuning of biological chromophores is a major challenge in photobiology. We show here using large-scale full quantum chemical calculations of the green fluorescent protein that state-of-the-art coupled-cluster calculations provide accurate excitation energies and detailed insight about specific environmental effects. We obtain vertical excitation energies of 3.13 eV (396 nm) and 2.68 eV (463 nm), which are in quantitative agreement with the experimental absorption energies of 3.12 eV (397 nm) and 2.61 eV (475 nm) for the A- and B-forms of the protein. We find that the protein environment redshifts the absorption spectra by ∼0.56 eV and ∼0.22 eV for the two states, which can be attributed to ∼80% electrostatic effects and ∼20% steric effects.

Chromophore

Electrostatics

10.1039/c3cp00058c

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Citations (51)