A5071067439- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Machine Learning in Materials Science
- Advanced Condensed Matter Physics
- Catalysis and Oxidation Reactions
- Physics of Superconductivity and Magnetism
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Molecular Junctions and Nanostructures
- Magnetism in coordination complexes
- Porphyrin and Phthalocyanine Chemistry
- Advanced NMR Techniques and Applications
- Molecular spectroscopy and chirality
- Photochemistry and Electron Transfer Studies
- Electron Spin Resonance Studies
- Metal-Organic Frameworks: Synthesis and Applications
- Magnetic and transport properties of perovskites and related materials
- Metal complexes synthesis and properties
- Laser-Matter Interactions and Applications
- Crystal structures of chemical compounds
- Atomic and Molecular Physics
- Crystallography and molecular interactions
- Molecular Spectroscopy and Structure
- Computational Drug Discovery Methods
- Magnetic properties of thin films
Max Planck Institute for Solid State Research
2019-2023
University of Göttingen
2015-2022
Data61
2020
Commonwealth Scientific and Industrial Research Organisation
2020
The Dodd-Walls Centre for Photonic and Quantum Technologies
2020
University of Cambridge
2020
King's College London
2020
University of Waterloo
2020
University of Iowa
2020
Massey University
2020
In this Article we describe the OpenMolcas environment and invite computational chemistry community to collaborate. The open-source project already includes a large number of new developments realized during transition from commercial MOLCAS product platform. paper initially describes technical details software development This is followed by brief presentations many methods, implementations, features program suite. These include novel wave function methods such as stochastic complete active...
We present NECI, a state-of-the-art implementation of the Full Configuration Interaction Quantum Monte Carlo (FCIQMC) algorithm, method based on stochastic application Hamiltonian matrix sparse sampling wave function. The program utilizes very powerful parallelization and scales efficiently to more than 24 000 central processing unit cores. In this paper, we describe core functionalities NECI its recent developments. This includes capabilities calculate ground excited state energies,...
In this work, we demonstrate how to efficiently compute the one- and two-body reduced density matrices within spin-adapted full configuration interaction quantum Monte Carlo (FCIQMC) method, which is based on graphical unitary group approach (GUGA). This allows us use GUGA-FCIQMC as a spin-pure (CI) eigensolver complete active space self-consistent field (CASSCF) procedure hence stochastically treat spaces far larger than conventional CI solvers while variationally relaxing orbitals for...
The large antiferromagnetic exchange coupling in the parent high-${T}_{\mathrm{c}}$ cuprate superconductors is believed to play a crucial role pairing superconducting carriers. recent observation of superconductivity hole-doped infinite-layer (IL-) ${\mathrm{NdNiO}}_{2}$ brings fore relevance magnetic superconductors, particularly because no ordering observed undoped IL-${\mathrm{NdNiO}}_{2}$, unlike copper oxides. Here, we investigate electronic structure and nature...
Abstract Stochastic‐CASSCF and DMRG procedures have been utilized to quantify the role of electron‐correlation mechanisms that, in an Fe‐porphyrin model system, are responsible for differential stabilization 3 E g over 5 A 1 state. Orbital entanglement diagrams CI coefficients wave function a localized orbital basis allow effective interpretation charge‐transfer configurations. preliminary version Stochastic Generalized Active Space Self‐Consistent Field method has developed is here...
An algorithm to perform stochastic generalized active space calculations, Stochastic-GAS, is presented, that uses the Slater determinant based FCIQMC as configuration interaction eigensolver. Stochastic-GAS allows construction and optimization of preselected truncated wave functions, either reduce computational costs large function optimizations, or probe role specific electron correlation pathways. As for conventional GAS procedure, preselection on selection multiple subspaces while...
In this article, we demonstrate that a first-order spin penalty scheme can be efficiently applied to the Slater determinant based Full-CI Quantum Monte Carlo (FCIQMC) algorithm, as practical route toward purification. Two crucial applications are presented validity and robustness of scheme: 1Δg ← 3Σg vertical excitation in O2 key gaps [Mn3(IV)O4] cluster. absence robust adaptation/purification technique, both would unattainable by ground state methods, with any starting wave function...
Abstract The equilibrium structure and rovibrational energies of nitrous oxide (N 2 O) in its electronic ground state ( X 1 Σ + ) are derived from a high-level ab initio potential energy function (PEF). This PEF is based on composite approach with the basic contribution given by explicitly correlated coupled-cluster (CC) calculations. Smaller contributions include corrections due to inner-shell correlation, scalar-relativistic effects higher-order correlation up iterative pentuple...
Abstract In this work, we present a fully automated method for the construction of chemically meaningful sets hierarchical nonredundant internal coordinates (ICs; also commonly denoted as Z ‐matrices) from Cartesian molecular system. Particular focus is placed on avoiding ill‐definitions angles and dihedrals due to linear arrangements atoms, consistently guarantee well‐defined transformation coordinates, even after structural changes. The representations thus obtained are particularly well...
An accurate near-equilibrium potential energy surface (PES) for CNC+ is constructed based on a high-level composite ab initio method. By combining explicitly correlated all-electron CCSD(T)-F12b with scalar relativistic effects and higher order correlation up to coupled cluster theory singles, doubles, triples quadruples (CCSDTQ) we achieve convergence in the wavenumbers of fundamentals ca. 1 cm−1. Rovibrational energies are calculated variational approach vibrational term rotational...
Multiconfigurational methods are applied to study electronic properties and structural changes in the highly flexible metal-organic framework MIL53(Cr). Via calculated bending potentials of angles, that change most during phase transition, it is verified high flexibility this material not a question about special coordination chemistry, but overall linking framework. The complex posseses demanding structure with delocalized spin density, antifferomagnetic coupling multi-state character...
The equilibrium geometry and rovibrational spectroscopic parameters of the three astrochemical ions l-C3H+, l-SiC2H+, C3N− some their isotopologues are obtained from high-level quantum chemical calculations. A composite approach based on explicitly correlated coupled-cluster method CCSD(T)-F12b, that further includes core correlation, scalar-relativistic effects most importantly higher order correlation beyond CCSD(T) is used to set-up near-equilibrium potential energy surface (PES). these...
<div>Stochastic-CASSCF and DMRG procedures have been utilized to quantify the role of electron correlation mechanisms that in a Fe-porphyrin model system are responsible for differential stabilization triplet over quintet state. Orbital entanglement diagrams CI-coefficients wave function localised orbital basis allow an effective interpretation charge-transfer configurations. A preliminary version <i>Stochastic Generalized Active Space Self-Consistent Field</i> method has...
In this paper, we propose an improved excitation generation algorithm for the full configuration interaction quantum Monte Carlo method, which is particularly effective in systems described by localized orbitals. The method extension of precomputed heat-bath strategy Holmes et al., with more sampling double excitations and a novel approach nonuniform single excitations. We demonstrate effectiveness chain 30 hydrogen atoms atom-localized orbitals, stack benzene molecules, Fe(II)-porphyrin...
Abstract Three new zinc(II) coordination units [Zn(1–3)] based on planar‐directing tetradentate Schiff base‐like ligands H 2 (1 – 3) were synthesized. Their solid‐state structures investigated by single crystal X‐ray diffraction, showing the tendency to overcome square‐planar sphere axial ligation. Affinity in solution towards ligation has been tested extended spectroscopic studies, both absorption and emission mode. The electronic spectrum of pyridine complex [Zn(1)(py)] characterized...
In this article we describe the OpenMolcas environment and invite computational chemistry community to collaborate. The open-source project already includes a large number of new developments realized during transition from commercial MOLCAS product platform. paper initially describes technical details software development This is followed by brief presentations many methods, implementations, features program suite. These include novel wave function methods such as stochastic complete active...
An algorithm to perform stochastic generalized active space calculations, Stochastic-GAS, is presented, that uses the Slater determinant based FCIQMC as configuration interaction eigensolver. Stochastic-GAS allows construction and optimization of preselected truncated wave functions, either reduce computational costs large function optimizations, or probe role specific electron correlation pathways. As for conventional GAS procedure, preselection on selection multiple subspaces while...
In this article we describe the OpenMolcas environment and invite computational chemistry community to collaborate. The open-source project already includes a large number of new developments realized during transition from commercial MOLCAS product platform. paper initially describes technical details software development This is followed by brief presentations many methods, implementations, features program suite. These include novel wave function methods such as stochastic complete active...
In this article we describe the OpenMolcas environment and invite computational chemistry community to collaborate. The open-source project already includes a large number of new developments realized during transition from commercial MOLCAS product platform. paper initially describes technical details software development This is followed by brief presentations many methods, implementations, features program suite. These include novel wave function methods such as stochastic complete active...
Stochastic-CASSCF and DMRG procedures have been utilized to quantify the role of electron correlation mechanisms that in a Fe-porphyrin model system are responsible for differential stabilization triplet over quintet state. Orbital entanglement diagrams CI-coefficients wave function localised orbital basis allow an effective interpretation charge-transfer configurations. A preliminary version Stochastic Generalized Active Space Self-Consistent Field method has developed is here introduced...
In this work, we present a fully automated method for the construction of chemically meaningful sets non-redundant internal coordinates (also commonly denoted as Z-matrices) from cartesian molecular system. Particular focus is placed on avoiding ill-definitions angles and dihedrals due to linear arrangements atoms, consistently guarantee well-defined transformation coordinates, even after structural changes. The representations thus obtained are particularly well suited pathway in...
In this paper we propose an improved excitation generation algorithm for the full configuration interaction quantum monte carlo (FCIQMC) method, which is particularly effective in systems described by localized orbitals. The method extension of precomputed heat-bath (PCHB) strategy Holmes et al., with more sampling double excitations and a novel approach non-uniform single excitations. We demonstrate effectiveness chain 30 hydrogen atoms atom-localized orbitals, stack benzene molecules,...
In this paper we propose an improved excitation generation algorithm for the full configuration interaction quantum monte carlo (FCIQMC) method, which is particularly effective in systems described by localized orbitals. The method extension of precomputed heat-bath (PCHB) strategy Holmes et al., with more sampling double excitations and a novel approach non-uniform single excitations. We demonstrate effectiveness chain 30 hydrogen atoms atom-localized orbitals, stack benzene molecules,...
Stochastic-CASSCF and DMRG procedures have been utilized to quantify the role of electron correlation mechanisms that in a Fe-porphyrin model system are responsible for differential stabilization triplet over quintet state. Orbital entanglement diagrams CI-coefficients wave function localised orbital basis allow an effective interpretation charge-transfer configurations. A preliminary version Stochastic Generalized Active Space Self-Consistent Field method has developed is here introduced...
In this Letter we demonstrate that a first-order spin penalty scheme can be efficiently applied to the Slater determinant based Full-CI Quantum Monte-Carlo (FCIQMC) algorithm, as practical route towards purification. Two crucial applications are presented validity and robustness of scheme; 1∆g ← 3Σg vertical excitation in O2 , key gaps [Mn3 O4]3+ cluster. absence robust adaptation/purification technique, both would unattainable by ground state methods, with any starting wave function...