Article
Chemistry, Physical
Rulin Feng, Thomas J. Duignan, Jochen Autschbach
Summary: The X2C relativistic nuclear hyperfine magnetic field operators were incorporated in ab initio wavefunction calculations at the multireference restricted active space level for calculations of nuclear hyperfine magnetic properties. The method was tested by calculations of electron-nucleus hyperfine coupling constants, showing reasonably good agreement with experimental data. The approach overcomes limitations of previous implementations and demonstrates good agreement with experimental data on various systems.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Physical
Haibing Meng, Yongqiang Chai, Chong Zhao, Mingzhe Nie, Chunru Wang, Taishan Wang
Summary: In this study, a paramagnetic metallofullerene Sc3C2@C-80 dimer with two spin centers was synthesized and its varied paramagnetic properties were demonstrated in different media. The modulation of EPR signals by controlling dynamic motion showed the potential for fine tuning of the material's magnetic properties. Overall, the Sc3C2@C-80 dimer represents a promising candidate for new magnetic materials with unique characteristics.
Article
Chemistry, Physical
Marti Gimferrer, Pedro Salvador
Summary: In the IQA approach, molecular energy is decomposed into atomic and diatomic contributions. This study critically analyzes two fully additive approaches for the IQA decomposition of the KS-DFT energy and compares their performance. The results show that both methodologies behave similarly for all systems considered, and the diatomic exchange-correlation components are less negative in the SM-IQA approach compared to Hartree-Fock, which is consistent with the effect of electron correlation on covalent bonds. Additionally, a new general scheme to minimize numerical error in the sum of two-electron energy contributions is described.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Roland Erickson, Anders Lund
Summary: This paper presents a study on the simulation of powder ENDOR spectra using exact and perturbation methods. The simulation results provide the anisotropic hyperfine and nuclear quadrupole coupling constants of organic radicals. The study shows that the hfc values of certain aromatic cations trapped in disordered matrices might be more accurate than those previously reported using regular EPR. Additionally, adjusting the simulation parameters can improve the agreement with experimental spectra.
Article
Energy & Fuels
Margarita A. Sadovnikova, Fadis F. Murzakhanov, Georgy Mamin, Marat R. Gafurov
Summary: This study analyzed the electron-nuclear interactions of VP complexes in oil asphaltenes and investigated the complex hyperfine structure related to nuclear spins, providing insights into the transformation of asphaltenes.
Article
Chemistry, Physical
Maciej Witwicki, Agnieszka Lewinska, Andrew Ozarowski
Summary: In this work, a mono-semiquinonato complex of aluminum was synthesized from 1,2-dihydroxybenzene using a surprisingly short and uncomplicated procedure. The isolated product is an amorphous and porous solid that exhibits very good stability under ambient conditions, making it applicable in heterogeneous aerobic reactions. Characterization of its molecular and electronic structure was done using EPR spectroscopy and computational techniques, revealing the chemical composition and distribution of unpaired electrons in the complex.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Biochemistry & Molecular Biology
Alan Sena Pinheiro, Ricardo Gargano, Paulo Henrique Gomes dos Santos, Luiz Guilherme Machado de Macedo
Summary: This study investigated relativistic effects and Gaunt effects in polyatomic E121X(3) (X = F, Cl, Br) using different Hamiltonians. Results showed the importance of relativistic effects in obtaining reliable vibrational frequencies and the potential of using X2C spin-free Hamiltonian for cost-effective research on polyatomics, including superheavy elements. The comparison between ELF and Mulliken population analysis indicated bonding similarity between LaBr3 and E121Br(3).
JOURNAL OF MOLECULAR MODELING
(2021)
Article
Chemistry, Physical
Stefan Knecht, Michal Repisky, Hans Jorgen Aagaard Jensen, Trond Saue
Summary: The study introduces two methods to correct picture-change effects in exact two-component Hamiltonian framework, demonstrating high accuracy and computational efficiency in calculating molecular energies and properties, verified through experiments on two classes of molecules.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Yuri E. Kandrashkin, Art van der Est
Summary: This paper presents a model that describes the effect of incoherent state hopping on spin-polarized transient EPR signals. It shows that the size of the spin state space can be reduced by half and the system dynamics result in a redistribution of population among its eigenstates. Analytical expressions are derived for population redistribution rates and line shapes, and the calculated EPR signals are in good agreement with numerical solutions. The model is then used to investigate the influence of exciton hopping on triplet state transient EPR spectra.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Yannick J. Franzke, Jason M. Yu
Summary: We present a highly efficient implementation of the electron-nucleus hyperfine coupling matrix within the one-electron exact two-component (X2C) theory. Our implementation accurately reproduces the four-component fully relativistic parent results and has been extensively benchmarked on transition-metal compounds and rare-earth single-molecule magnets.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Multidisciplinary
Dennis Schaefter, Jonathan Wischnat, Lorenzo Tesi, J. Alejandro De Sousa, Edmund Little, Jake McGuire, Marta Mas-Torrent, Concepcio Rovira, Jaume Veciana, Floriana Tuna, Nuria Crivillers, Joris van Slageren
Summary: In this article, the spin dynamics of chlorinated triphenylmethyl organic radicals were investigated, revealing long ensemble coherence times and the achievement of two-qubit and individual qubit addressability in the biradical system. These results highlight the potential of molecular materials in the development of quantum architectures.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Dennis Schaefter, Jonathan Wischnat, Lorenzo Tesi, J. Alejandro De Sousa, Edmund Little, Jake McGuire, Marta Mas-Torrent, Concepcio Rovira, Jaume Veciana, Floriana Tuna, Nuria Crivillers, Joris van Slageren
Summary: General-purpose quantum computation and quantum simulation require precise and robust interqubit interactions in multi-qubit architectures, along with local addressability. Molecular systems, such as chlorinated triphenylmethyl organic radicals, show promise for large-scale quantum architectures due to their high degree of positionability and tailorability of interqubit interactions. This study demonstrates extraordinarily long coherence times up to 148 μs in the investigated molecular materials at temperatures below 100 K, and also showcases two-qubit and individual qubit addressability in the biradical system. These findings highlight the potential of molecular materials for the development of quantum architectures.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Goran Kovacevic
Summary: This article presents a method for solving three- and four-center Coulomb integrals in the solid spherical harmonic Gaussian basis by expanding them in terms of two-center integrals. By utilizing the two-electron Gaussian product rule and the addition theorem for solid spherical harmonics, four-center Coulomb integrals are reduced to a linear combination of two-center Coulomb integrals and one-center overlap integrals. With this approach, the resulting two-center Coulomb integrals can be further simplified into a simpler form, which can be related to the Boys function.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Marat Gafurov, Yulia Ganeeva, Tatyana Yusupova, Fadis Murzakhanov, Georgy Mamin
Summary: Petroleum asphaltenes are highly irritating components in oil systems, which pose challenges to extraction, transportation and processing of hydrocarbons. Despite decades of research, the structure of stable paramagnetic centers in petroleum systems remains unclear. This paper explores the use of various electron paramagnetic resonance (EPR) techniques to study petroleum asphaltenes and their solubility fractions, using a carbon-centered stable free radical as a probe. The results indicate that EPR-based approaches can be sensitive numerical tools for understanding the structure and disaggregation of asphaltenes.
Article
Chemistry, Inorganic & Nuclear
William J. M. Blackaby, Katie L. M. Harriman, Samuel M. Greer, Andrea Folli, Stephen Hill, Vera Krewald, Mary F. Mahon, Damien M. Murphy, Muralee Murugesu, Emma Richards, Elizaveta Suturina, Michael K. Whittlesey
Summary: A new series of homoleptic Ni(I) bis-N-heterocyclic carbene complexes with different torsion angles between the ligands have been reported. The complexes exhibit a strongly anisotropic g-tensor and the first excited state energy ranges from 270 to 650 cm(-1). The magnetic relaxation is dominated by Raman and direct processes, and the temperature dependence of the relaxation does not correlate with the torsion angle.
INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Patrick Federmann, Robert Mueller, Fabian Beckmann, Caroline Lau, Beatrice Cula, Martin Kaupp, Christian Limberg
Summary: This study focuses on Frustrated Lewis pairs (FLPs) composed of acidic alane and basic phosphane functions. The results show that CO2 can be bound to the FLPs via the C atom at the phosphane functions and the two O atoms at the Al centers. The binding strength is determined by the residues at the Al centers, and higher electronegative residues lead to higher thermodynamic stabilization and higher barriers.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Physical
Marc Reimann, Martin Kaupp
Summary: This article presents an analytical approach to compute the excess entropy of solvation at constant pressure in 3D-RISM calculations. The approach considers changes in the macroscopic dielectric constant of the solvent with temperature and density variations. It gives reasonable results for self-consistently determined electrostatics, particularly for entropy differences, and shows promise in obtaining (semi)quantitative agreement with experimental reaction entropies.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Chemistry, Multidisciplinary
Robin Grotjahn, Martin Kaupp
Summary: Local hybrid functionals (LHs) show broad applicability in energetics research, especially demonstrating excellent performance in transition-metal complexes and mixed-valence systems.
ISRAEL JOURNAL OF CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Simon G. Rachor, Robert Mueller, Martin Kaupp, Thomas Braun
Summary: The hydrogen bonding in the Au(I) complex [Au(F . HF)(SPhos)] has been analyzed by IR and NMR measurements and confirmed by DFT calculations. Comparisons to complexes with NHC ligands showed similar bonding situations. Single crystal X-ray diffraction studies demonstrated the presence of halogen bonds to Au(I) fluorido complexes in the solid state.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Stefan Sander, Elizabeth J. Cosgrove, Robert Mueller, Martin Kaupp, Thomas Braun
Summary: The Pt complexes react with HF to form polyfluorido complexes, which can be converted into fluoride derivatives. The NMR data of the polyfluorido complexes reveal hydrogen bonding between the fluorido ligand and HF molecules as well as the indolylphosphine ligand.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Physical
Susanne Fuerst, Matthias Haasler, Robin Grotjahn, Martin Kaupp
Summary: We present the implementation of range-separated local hybrid functionals (RSLHs) in TURBOMOLE, allowing for efficient calculation of ground-state and excitation energies. Compared to regular local hybrid functionals (LHs), RSLHs have similar scaling with system or basis set size and increase total timings by a factor of 2-3. A specific RSLH, omega LH22t, is optimized for atomization energies and reaction barriers, showing superior performance for a wide range of ground-state and excited-state quantities. It approaches the accuracy of the best local hybrids to date for various excitation energies and performs remarkably for charge-transfer excitations.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Marc Reimann, Martin Kaupp
Summary: A new composite method based on multireference methods is introduced for calculating spin-crossover energies in 3d transition-metal complexes. This method shows high accuracy in reproducing MRCISD+Q/CBS results for atomic ions and provides unprecedented agreement with experiment for molecular complexes in aqueous solution. It is also discovered that the lowest-energy excitation frequently used for evaluating quantum-chemical methods in the Fe3+ system does not originate from the iron(III) hexaqua complex in solution.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Multidisciplinary
Domenique Herbstritt, Pooja Tomar, Robert Mueller, Martin Kaupp, Thomas Braun
Summary: The N-heterocyclic deoxyfluorinating agent SIMesF2 was synthesized by nucleophilic fluorination of N,N-1,3-dimesityl-2-chloroimidazolidinium chloride (3) at room temperature. SIMesF2 can deoxyfluorinate carboxylic acids and alcohols and convert benzaldehyde into difluorotoluene. Mechanistic studies by NMR spectroscopy suggest reaction pathways of the carboxylic acid to acyl fluoride via outer-sphere fluorinations at an imidazolidinium ion by polyfluoride. DFT studies give further insight by exploring mechanistic details which distinguish the fluorination of aldehydes from that of carboxylic acids. Furthermore, a consecutive reaction sequence for the oxidation of an aldehyde followed by in situ fluorination of the generated carboxylic acid was developed.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Inorganic & Nuclear
Konrad Kretschmar, Vladimir Pelmenschikov, Martin Kaupp, Thomas Braun, Philipp Wittwer, Simon Rachor, Jesvita Cardozo
Summary: A set of bimetallic complexes based on iridium and rhodium with various bridging ligands were synthesized and studied for catalytic hydrodefluorination reactions using molecular hydrogen and sodium tert-butoxide. The effects of ligand variation, nuclearity, and metal identity were investigated to optimize the hydrodefluorination process.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Physical
Artur Wodynski, Alexei V. Arbuznikov, Martin Kaupp
Summary: Recent work has developed a simplified method for constructing adiabatic-connection factors for strong-correlation-corrected local hybrids (scLHs) based on a comparison of semi-local and exact exchange-energy densities. By using either a modified Becke-Roussel or a simpler Perdew-Burke-Ernzerhof (PBE) energy density, competitive scLHs, namely scLH23t-mBR and scLH23t-tPBE functionals, can be derived. These functionals exhibit low fractional spin errors and good performance for weakly correlated situations. Furthermore, preliminary attempts towards more detailed modeling of the local adiabatic connection have been made to reduce unphysical local maxima in spin-restricted bond-dissociation energy curves.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Matthias Haasler, Toni M. Maier, Martin Kaupp
Summary: This paper reports a new local hybrid functional that improves the position-dependent exact-exchange admixture in the core region while retaining or partly improving upon the high accuracy in the valence region. The suggested new pt-LMFs are based on a Pade form and modify the previously used ratio between von Weizsacker and Kohn-Sham local kinetic energies to enable improved approximations to the high-density and iso-orbital limits relevant for the innermost core region. The LHs are completed by a calibration function that minimizes spurious nondynamical correlation effects caused by gauge ambiguities and meta-GGA correlation.
JOURNAL OF COMPUTATIONAL CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Susanne M. Rupf, Robin Sievers, Paulin S. Riemann, Marc Reimann, Martin Kaupp, Carlo Fasting, Moritz Malischewski
Summary: We report the preparation and structural characterization of the first persilylated metallocene via the metalation of decabromoferrocene. Stepwise lithium-halogen exchange yields complex mixtures of polysilylated compounds, including the targeted decasilylated ferrocene. The findings were used to develop a high-yielding and simple preparation method to generate a tenfold substituted overcrowded ferrocene.
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Physical
Susanne Fuerst, Matthias Haasler, Robin Grotjahn, Martin Kaupp
Summary: We successfully implemented range-separated local hybrid functionals (RSLHs) into the TURBOMOLE program package for the first time, allowing for the computation of ground-state energies, nuclear gradients, and excitation energies. The computational effort of RSLHs is comparable to regular local hybrid functionals (LHs), with a 2-3 times increase in overall timings. The advanced RSLH, omega LH22t, performs well for a wide range of evaluations.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Susanne Fuerst, Martin Kaupp, Artur Wodynski
Summary: This paper presents a highly flexible strong-correlation-corrected range-separated local hybrid (scRSLH) method, which reduces position-dependent exact-exchange admixtures and corrects delocalization errors in abnormal open-shell situations. The scRSLH method shows promising potential in accurately computing quasiparticle energies and thermochemical and kinetic parameters for complex molecular or condensed-phase systems.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)