Andreas Köhn
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View article: Bistability in Palladium Complexes with Two Different Redox‐Active Ligands of Orthogonal Charge Regimes
Bistability in Palladium Complexes with Two Different Redox‐Active Ligands of Orthogonal Charge Regimes Open
Electronically bistable molecular coordination compounds are obtained by a combination of two different redox‐active ligands with orthogonal charge regimes in square‐planar palladium complexes. Thereby, the first complexes are obtained in …
View article: Machine-learning interatomic potentials achieving CCSD(T) accuracy for systems with extended covalent networks and van der Waals interactions
Machine-learning interatomic potentials achieving CCSD(T) accuracy for systems with extended covalent networks and van der Waals interactions Open
Machine-learning interatomic potentials (MLIPs) enable large-scale atomistic simulations at moderate computational cost while retaining ab initio accuracy. MLIPs trained on coupled-cluster data, particularly CCSD(T), have emerged a promisi…
View article: A Design Space for Visualization Transitions of 3D Spatial Data in Hybrid AR-Desktop Environments
A Design Space for Visualization Transitions of 3D Spatial Data in Hybrid AR-Desktop Environments Open
We present a design space for animated transitions of the appearance of 3D spatial datasets in a hybrid Augmented Reality (AR)-desktop context. Such hybrid interfaces combine both traditional and immersive displays to facilitate the explor…
View article: The Spin-Phonon Relaxation Mechanism of Single-Molecule Magnets in the Presence of Strong Exchange Coupling
The Spin-Phonon Relaxation Mechanism of Single-Molecule Magnets in the Presence of Strong Exchange Coupling Open
Magnetic relaxation in coordination compounds is largely dominated by the interaction of the spin with phonons. Although a comprehensive understanding of spin-phonon relaxation has been achieved for mononuclear complexes, only a qualitativ…
View article: Multireference Coupled‐Cluster Theory: The Internally Contracted Route
Multireference Coupled‐Cluster Theory: The Internally Contracted Route Open
Transferring the success of the coupled‐cluster expansion for single‐determinant references to multireference cases remains a challenge. The main dilemma is a proper merge of the exponential ansatz, required for extensivity of the correlat…
View article: Simplified Multireference Coupled‐Cluster Methods: Hybrid Approaches With Averaged Coupled Pair Theories
Simplified Multireference Coupled‐Cluster Methods: Hybrid Approaches With Averaged Coupled Pair Theories Open
We define an approximation to the internally contracted multireference coupled‐cluster method with single and double excitations by a hybrid approach. The rationale is to treat the external pair energy contributions by the coupled‐cluster …
View article: The Impact of Donor-Orientation on the Emission Properties of Chlorinated Trityl Radicals
The Impact of Donor-Orientation on the Emission Properties of Chlorinated Trityl Radicals Open
Chlorinated trityl radicals functionalized with electron-donating groups are promising red-emitting materials for optoelectronic and spintronic applications, overcoming the spin-statistical limit of conventional emitters. Donor functionali…
View article: The Impact of Donor-Orientation on the Emission Properties of Chlorinated Trityl Radicals
The Impact of Donor-Orientation on the Emission Properties of Chlorinated Trityl Radicals Open
Chlorinated trityl radicals functionalized with electron-donating groups are promising red-emitting materials for optoelectronic and spintronic applications, overcoming the spin-statistical limit of conventional emitters. Donor functionali…
View article: The spin-phonon relaxation mechanism of single-molecule magnets in the presence of strong exchange coupling
The spin-phonon relaxation mechanism of single-molecule magnets in the presence of strong exchange coupling Open
Magnetic relaxation in coordination compounds is largely dominated by the interaction of the spin with phonons. Large zero-field splitting and exchange coupling values have been empirically found to strongly suppress spin relaxation and ha…
View article: Electronic structure of mononuclear and radical-bridged dinuclear cobalt(II) single-molecule magnets
Electronic structure of mononuclear and radical-bridged dinuclear cobalt(II) single-molecule magnets Open
Metal-organic compounds that feature magnetic bistability (single-molecule magnets) have been proposed as data bits for magnetic storage, but progress has been slow. Four-coordinate cobalt(II) complexes have been shown to be a robust, air-…
View article: Cyclohepta[<i>def</i>]fluorene as a bistable molecule: first principles studies on its electronic structure and the effects of benzo-extension, substitution and solvation
Cyclohepta[<i>def</i>]fluorene as a bistable molecule: first principles studies on its electronic structure and the effects of benzo-extension, substitution and solvation Open
Cyclohepta[ def ]fluorene is a bistable molecule with a polar closed-shell singlet and a nonpolar triplet state. Using state-of-the-art quantum-chemical methods, we show how the relative stabilty of the states can be tuned by chemical modi…
View article: Performance Tests of the Second-Order Approximate Internally Contracted Multireference Coupled-Cluster Singles and Doubles Method icMRCC2
Performance Tests of the Second-Order Approximate Internally Contracted Multireference Coupled-Cluster Singles and Doubles Method icMRCC2 Open
Benchmark results are presented for the second-order approximation of the internally contracted multireference coupled-cluster method with single and double excitations, icMRCC2 [Köhn, Bargholz, J. Chem. Phys. 2019, 151, 041106], which was…
View article: Capabilities and limits of the unitary coupled-cluster approach with generalized two-body cluster operators
Capabilities and limits of the unitary coupled-cluster approach with generalized two-body cluster operators Open
Unitary cluster expansions of the electronic wavefunction have recently gained much interest because of their use in conjunction with quantum algorithms. In this contribution, we investigate some aspects of an ansatz, using generalized two…
View article: MolecuSense: Using Force-Feedback Gloves for Creating and Interacting with Ball-and-Stick Molecules in VR
MolecuSense: Using Force-Feedback Gloves for Creating and Interacting with Ball-and-Stick Molecules in VR Open
We contribute MolecuSense, a virtual version of a physical molecule\nconstruction kit, based on visualization in Virtual Reality (VR) and\ninteraction with force-feedback gloves. Targeting at chemistry education, our\ngoal is to make virtu…
View article: CCDC 2189955: Experimental Crystal Structure Determination
CCDC 2189955: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: High-accuracy Rb$_{2}^+$ interaction potentials based on coupled cluster calculations
High-accuracy Rb$_{2}^+$ interaction potentials based on coupled cluster calculations Open
This work discusses a protocol for constructing highly accurate potential energy curves (PECs) for the lowest two states of Rb$_{2}^+$, i.e. $X\,{}^2Σ{_g^+}$ and $(1) {}^2Σ{_u^+}$, using an additivity scheme based on coupled-cluster theory…
View article: MolecuSense: Using Force-Feedback Gloves for Creating and Interacting with Ball-and-Stick Molecules in VR
MolecuSense: Using Force-Feedback Gloves for Creating and Interacting with Ball-and-Stick Molecules in VR Open
We contribute MolecuSense, a virtual version of a physical molecule construction kit, based on visualization in Virtual Reality (VR) and interaction with force-feedback gloves. Targeting at chemistry education, our goal is to make virtual …
View article: Chasing Polycyclic Natural Products: 5/6/5‐ or 5/6/6‐Carbotricyclic Scaffold Construction <i>via</i> Stereodivergent Diels‐Alder Reaction of Chiral Hydrindanes and Their Boron Complexes
Chasing Polycyclic Natural Products: 5/6/5‐ or 5/6/6‐Carbotricyclic Scaffold Construction <i>via</i> Stereodivergent Diels‐Alder Reaction of Chiral Hydrindanes and Their Boron Complexes Open
Chiral trans ‐hydrindanes (bicyclo[4.3.0]nonanes) are important building blocks of polycyclic natural products. In order to access 5/6/5‐ and 5/6/6‐carbotricyclic scaffolds scope and limitation of [4+2] cycloadditions of tetrahydroindanone…
View article: Thermally Averaged Magnetic Anisotropy Tensors via Machine Learning Based on Gaussian Moments
Thermally Averaged Magnetic Anisotropy Tensors via Machine Learning Based on Gaussian Moments Open
We propose a machine learning method to model molecular tensorial quantities, namely, the magnetic anisotropy tensor, based on the Gaussian moment neural network approach. We demonstrate that the proposed methodology can achieve an accurac…
View article: Thermally Averaged Magnetic Anisotropy Tensors via Machine Learning Based on Gaussian Moments
Thermally Averaged Magnetic Anisotropy Tensors via Machine Learning Based on Gaussian Moments Open
D-Tensor Data The reference data for 3500 configurations of [Co(N2S2O4C8H10)2]2− (CoSar), [Fe(tpa)Ph]− (FeTPAPh), and [Ni(HIM2−py)2NO3]+ (NiComplex) is generated employing Molpro package [1]. For more details see the original publication […
View article: Thermally Averaged Magnetic Anisotropy Tensors via Machine Learning Based on Gaussian Moments
Thermally Averaged Magnetic Anisotropy Tensors via Machine Learning Based on Gaussian Moments Open
D-Tensor Data The reference data for 3500 configurations of [Co(N2S2O4C8H10)2]2− (CoSar), [Fe(tpa)Ph]− (FeTPAPh), and [Ni(HIM2−py)2NO3]+ (NiComplex) is generated employing Molpro package [1]. For more details see the original publication […
View article: Limitations of coupled cluster approximations for highlyaccurate investigations of Rb$_2^+$
Limitations of coupled cluster approximations for highlyaccurate investigations of Rb$_2^+$ Open
We reveal limitations of several standard coupled-cluster (CC) methods with perturbation-theorybased noniterative or approximate iterative treatments of triple excitations when applied to thedetermination of highly accurate potential energ…
View article: Towards photoassociation processes of ultracold rubidium trimers
Towards photoassociation processes of ultracold rubidium trimers Open
We theoretically investigate the prospects for photoassociation (PA) of Rb$_3$, in particular at close range. We provide an overview of accessible states and possible transitions. The major focus is placed on the calculation of equilibrium…
View article: Liquid Crystalline Benzoic Acid Ester MIDA Boronates: Synthesis and Mesomorphic Properties
Liquid Crystalline Benzoic Acid Ester MIDA Boronates: Synthesis and Mesomorphic Properties Open
Two series of N-methyliminodiacetic acid (MIDA) boronates were prepared and their mesomorphic properties were investigated. MIDA-substituted benzoic acid esters were synthesized via the Mitsunobu reaction. The second series of MIDA benzyl …
View article: The Molpro quantum chemistry package
The Molpro quantum chemistry package Open
Molpro is a general purpose quantum chemistry software package with a long development history. It was originally focused on accurate wavefunction calculations for small molecules but now has many additional distinctive capabilities that i…
View article: CCDC 1939396: Experimental Crystal Structure Determination
CCDC 1939396: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: The Quasi‐Binary Acetonitriletriide Sr<sub>3</sub>[C<sub>2</sub>N]<sub>2</sub>
The Quasi‐Binary Acetonitriletriide Sr<sub>3</sub>[C<sub>2</sub>N]<sub>2</sub> Open
The first quasi‐binary acetonitriletriide Sr 3 [C 2 N] 2 has been synthesised and characterised. The nearly colourless crystals were obtained from the reaction of Sr metal, graphite, and elemental N 2 , generated by decomposition of Sr(N 3…
View article: Flavylium Salts: A Blooming Core for Bioinspired Ionic Liquid Crystals
Flavylium Salts: A Blooming Core for Bioinspired Ionic Liquid Crystals Open
Thermotropic ionic liquid crystals based on the flavylium scaffold have been synthesized and studied for their structure‐properties relationship for the first time. The mesogens were probed by differential scanning calorimetry (DSC), polar…