A5052839444- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Photochemistry and Electron Transfer Studies
- Molecular Junctions and Nanostructures
- Molecular spectroscopy and chirality
- Spectroscopy and Laser Applications
- Semiconductor Quantum Structures and Devices
- Advanced NMR Techniques and Applications
- Nonlinear Optical Materials Research
- History and advancements in chemistry
- Protein Structure and Dynamics
- DNA and Nucleic Acid Chemistry
- Various Chemistry Research Topics
- Electron Spin Resonance Studies
- X-ray Spectroscopy and Fluorescence Analysis
- Atomic and Molecular Physics
- Advanced Fluorescence Microscopy Techniques
- Perovskite Materials and Applications
- Neuroinflammation and Neurodegeneration Mechanisms
- Inorganic Fluorides and Related Compounds
- Catalysis and Oxidation Reactions
- Photoreceptor and optogenetics research
- Photochromic and Fluorescence Chemistry
- Nonlinear Optical Materials Studies
- Electron and X-Ray Spectroscopy Techniques
Heidelberg University
2013-2024
KTH Royal Institute of Technology
2017-2021
Korea Advanced Institute of Science and Technology
2021
Pohang University of Science and Technology
2021
Stockholm University
2020
AlbaNova
2020
Forschungsstätte der Evangelischen Studiengemeinschaft
2020
Linköping University
2016
A summary of the technical advances that are incorporated in fourth major release Q-Chem quantum chemistry program is provided, covering approximately last seven years. These include developments density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster perturbation theories, for electronically excited open-shell species, tools treating extended environments, algorithms walking on potential surfaces, analysis tools, energy...
This article summarizes technical advances contained in the fifth major release of Q-Chem quantum chemistry program package, covering developments since 2015. A comprehensive library exchange-correlation functionals, along with a suite correlated many-body methods, continues to be hallmark software. The methods include novel variants both coupled-cluster and configuration-interaction approaches based on algebraic diagrammatic construction variational reduced density-matrix methods. Methods...
The development of reliable theoretical methods and the provision efficient computer programs for investigation optical spectra photochemistry large molecules in general is one most important tasks contemporary chemistry. Here, we present an overview current features our implementation algebraic diagrammatic construction scheme polarisation propagator, which a versatile robust approach excited states their properties.
We report the development of a set excited-state analysis tools that are based on construction an effective exciton wavefunction and its statistical in terms spatial multipole moments. This does not only enable quantification location compactness individual hole electron densities but also correlation phenomena can be analyzed, which makes this procedure particularly useful when excitonic or charge-resonance effects interest. The methods first applied to bianthryl with focus elucidating...
An earlier proposed approach to molecular response functions based on the intermediate state representation (ISR) of polarization propagator and algebraic-diagrammatic construction (ADC) approximations is for first time employed calculations nonlinear properties. The two-photon absorption (TPA) spectra are considered. hierarchy first- second-order ADC/ISR computational schemes, ADC(1), ADC(2), ADC(2)-x, ADC(3/2), tested in applications H2O, HF, C2H4 (ethylene). calculated TPA compared with...
Density-based wave function analysis enables unambiguous comparisons of the electronic structure computed by different methods and removes ambiguity orbital choices. We use this tool to investigate performance spin-flip for several prototypical diradicals triradicals. In contrast previous calibration studies that focused on energy gaps between high- low spin-states, we focus properties underlying functions, such as number effectively unpaired electrons. Comparison density functional theory...
A scheme has been derived and implemented to gain computational access the full electronic part of Kramers-Heisenberg-Dirac (KHD) expression for resonant nonresonant inelastic scattering amplitudes. Our implementation this is based on complex polarization propagator in algebraic diagrammatic construction (ADC) framework within its intermediate state representation (ISR). The hierarchy second- third-order ADC/ISR schemes known as ADC(2), ADC(2)-x, ADC(3/2) considered, calculated X-ray (RIXS)...
We report on a combined theoretical and experimental study of core-excitation spectra gas liquid phase methanol as obtained with the use X-ray absorption spectroscopy (XAS) resonant inelastic scattering (RIXS). The electronic transitions are studied computational methods that include strict extended second-order algebraic diagrammatic construction [ADC(2) ADC(2)-x], restricted active space perturbation theory, time-dependent density functional theory—providing complete assignment near oxygen...
Abstract ADC‐connect ( adcc ) is a hybrid python / C++ module for performing excited state calculations based on the algebraic‐diagrammatic construction scheme polarization propagator (ADC). Key design goal to restrict this single purpose and facilitate connection external packages, example, obtaining Hartree–Fock references, plotting spectra, or modeling solvents. Interfaces four self‐consistent field codes have already been implemented, namely pyscf , psi4 molsturm veloxchem . The...
Abstract The Gator program has been developed for computational spectroscopy and calculations of molecular properties using real complex propagators at the correlated level wave function theory. Currently, focus lies on methods based algebraic diagrammatic construction (ADC) scheme up to third order perturbation An auxiliary Fock matrix‐driven implementation second‐order ADC method excitation energies realized with an underlying hybrid MPI/OpenMP parallelization suitable execution in...
An implementation of the damped linear response function, or complex polarization propagator, using algebraic-diagrammatic construction (ADC) scheme has been developed and utilized for calculation electric-dipole polarizabilities C6 dispersion coefficients. Four noble gases (He, Ne, Ar, Kr), five n-alkanes (methane, ethane, propane, butane, pentane), three carbonyls (formaldehyde, acetaldehyde, acetone), unsaturated hydrocarbons (ethene, acetylene, benzene) have treated with hierarchical set...
Expressions for the calculation of rotatory strengths using algebraic diagrammatic construction (ADC) scheme polarization propagator in both length and velocity gauges have been implemented. This enables simulation electronic circular dichroism (ECD) spectra at ADC level up to third order perturbation theory. The ADC(n) methods produce comparable accuracy those obtained with coupled cluster corresponding approximation levels, as evaluated methyloxirane, methylthiirane, dimethyloxirane,...
Different approaches to mixed-order algebraic-diagrammatic construction (ADC) schemes are investigated. The performance of two different strategies for scaling third-order contributions the ADC secular matrix is evaluated. Both considered employ a single tuning parameter and conserve general properties inherent all methods, such as hermiticity size-consistency. first approach, scaled-matrix ADC[(2) + x(3)], scales occurring in ADC(3) equally leads an improvement accuracy excitation energies...
When dealing with approximate wave functions, molecular properties can be computed either as expectation values or derivatives of the energy respect to a corresponding perturbation. In this work, intermediate state representation (ISR) formalism for computation is compared Lagrange following derivative ansatz, which are two alternative approaches neither one considered superior in general. Within ISR formalism, terms included up given order perturbation theory only, while all accounted...
Third-order nonlinear optical (NLO) properties of polymethine dyes have been widely studied for applications such as all-optical switching. However, the limited accuracy current computational methodologies has prevented a comprehensive understanding nature lowest excited states and their influence on molecular NLO properties. Here, attention is paid to excited-state energies energetic ratio, these characteristics impact figure-of-merit For series model polymethines, we compare several...
The modification of the algebraic-diagrammatic construction (ADC) scheme for polarization propagator using ground-state coupled-cluster (CC) instead Møller-Plesset (MP) amplitudes, referred to as CC-ADC, is extended calculation molecular properties, in particular, dipole polarizabilities. Furthermore, addition CC with double excitations (CCD), single and (CCSD) amplitudes can be used, also second-order transition moments ADC(3/2) method. In CC-ADC(2) variants, MP correlation coefficients...
Anionic pentameric thiophene acetates can be used for fluorescence detection and diagnosis of protein amyloid aggregates. Replacing the central unit by benzothiadiazole (BTD) or quinoxaline (QX) leads to large emission shifts basic spectral features have been reported [Chem. Eur. J. 2015, 21, 15133-13137]. Here we present new detailed experimental results solvent effects, time-resolved examples employing multi-photon microscopy lifetime imaging. Quantum chemical response calculations...
For the calculation of adiabatic singlet-triplet gaps (STG) in diradicaloid systems spin-flip (SF) variant algebraic diagrammatic construction (ADC) scheme for polarization propagator third order perturbation theory (SF-ADC(3)) has been applied. Due to methodology SF approach singlet and triplet states are treated on an equal footing since they part same determinant subspace. This leads a systematically more accurate description of, e.g., than with corresponding non-SF single-reference...
Employing an intermediate state representation (ISR) approach, Hermitian second-order methods for the calculation of electronic excitation energies are presented and compared in detail. These comprise algebraic–diagrammatic construction scheme polarization propagator, a hybrid ISR based on traditional coupled-cluster theory as well two similar approaches unitary (UCC) ansatz. Although strict perturbation-theoretical framework all prove to be identical, differences emerge when corresponding...
The efficient implementation of the third-order unitary coupled-cluster scheme (UCC3) for calculation excited electronic states is reported. UCC3 and its second-order UCC2 variant have been benchmarked compared to Jacquemin's recently introduced, as well Thiel's well-established, benchmark sets excitation energies oscillator strengths. For latter, 134 singlet 71 triplet 28 small- medium-sized organic molecules has revealed that exhibits a mean error standard deviation 0.36 ± 0.41 eV 0.22...
An ad hoc modification of the algebraic-diagrammatic construction (ADC) scheme for polarization propagator is presented. Within this approach, all first-order Møller-Plesset correlation coefficients occurring in second-order ADC secular matrix are replaced by amplitudes obtained from a coupled cluster doubles (CCD) calculation. This new hybrid method, denoted CCD-ADC(2), has been tested on series small diatomic and triatomic molecules benchmarked with respect to Thiel's benchmark set...
Analytic gradient expressions for the algebraic diagrammatic construction (ADC) scheme polarization propagator up to third order are derived using a Lagrangian approach. An implementation within Q-CHEM electronic structure package excited-state nuclear gradients of ADC(2), ADC(2)-x, and ADC(3) models based on restricted unrestricted Hartree-Fock references is presented. Details applicability newly geometry optimizations quality resulting structures discussed.
Singlet fission (SF) has the potential to dramatically increase solar cell efficiency by converting one singlet exciton two free triplet excitons via a correlated pair intermediate. Identification and characterization of excited states involved in SF are great importance for understanding fundamentals SF. Despite their importance, it is still nontrivial distinguish various species transient absorption spectra due spectral overlaps ultrashort lifetimes. Theoretical modeling its electronically...
Excited-state rotatory strengths are reported for the first time at a correlated ab initio level, here with algebraic diagrammatic construction scheme of polarization propagator up to third order. To demonstrate capabilities this computational approach, gas phase S1 electronic circular dichroism spectra bicyclic ketones (1R)-camphor, (1R)-norcamphor, and (1R)-fenchone have been calculated ADC(3) level theory. Furthermore, solution excited-state energetically lowest conformer...
We present the derivation and implementation of complex, frequency-dependent polarizabilities for excited states using algebraic–diagrammatic construction polarization propagator (ADC) its intermediate state representation. Based on complex polarizability, we evaluate C6 dispersion coefficients states. The methodology is implemented up to third order in perturbation theory Python-driven adcc toolkit development application ADC methods. exemplify approach illustrative model systems compare it...