A5049075661- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Atomic and Molecular Physics
- Advanced NMR Techniques and Applications
- Molecular Junctions and Nanostructures
- Atmospheric Ozone and Climate
- Inorganic Fluorides and Related Compounds
- Molecular spectroscopy and chirality
- Magnetism in coordination complexes
- Photochemistry and Electron Transfer Studies
- Molecular Spectroscopy and Structure
- Quantum, superfluid, helium dynamics
- Nuclear physics research studies
- Mass Spectrometry Techniques and Applications
- Matrix Theory and Algorithms
- Semiconductor Quantum Structures and Devices
- Quantum and electron transport phenomena
- Catalysis and Oxidation Reactions
- Spectroscopy and Laser Applications
- Nonlinear Optical Materials Research
- Laser-Matter Interactions and Applications
- Advanced Physical and Chemical Molecular Interactions
- Quantum Dots Synthesis And Properties
- High-pressure geophysics and materials
- Chemical Thermodynamics and Molecular Structure
Aarhus University
2016-2025
Auburn University
2019
Oak Ridge National Laboratory
2019
The University of Texas at Austin
2016
Laboratoire de Chimie et Physique Quantiques
2012
Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes
2012
Université Toulouse III - Paul Sabatier
2012
Lundbeck (Denmark)
2012
Lundbeck Foundation
2007-2011
University of Helsinki
1990-2008
Dalton is a powerful general-purpose program system for the study of molecular electronic structure at Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, Møller-Plesset, configuration-interaction, and coupled-cluster levels theory. Apart from total energy, wide variety properties may be calculated using these electronic-structure models. Molecular gradients Hessians are available geometry optimizations, dynamics, vibrational studies, whereas magnetic resonance optical...
We have examined the response of an exact and MCSCF reference state to a general time-dependent field. The time development both been parametrized in terms explicit exponential transformations. has determined by requiring Ehrenfest theorem be satisfied through each order interaction between molecular system used evaluate linear, quadratic, cubic functions. It shown how large variety properties may expressed these also demonstrated that containing electric dipole operator equivalent forms...
A restricted active space (RAS) wave function is introduced, which encompasses many commonly used CI expansions. highly vectorized algorithm developed for full and other RAS calculations. The based on Slater determinants expressed as products of alphastrings betastrings lends itself to a matrix indexing C(Iα, Iβ ) the vector. major features are: (1) intermediate summation over replaced by two summations strings, number only square root determinants. (2) Intermediate strings outside avoided...
We present a new theoretical framework, called Multiconfiguration Pair-Density Functional Theory (MC-PDFT), which combines multiconfigurational wave functions with generalization of density functional theory (DFT). A self-consistent-field (MCSCF) function correct spin and space symmetry is used to compute the total electronic density, its gradient, on-top pair kinetic Coulomb contributions energy. then use calculate remaining part energy, we call on-top-density-functional energy in contrast...
Equilibrium structures have been determined for 19 molecules using least-squares fits involving rotational constants from experiment and vibrational corrections high-level electronic-structure calculations. obtained by this procedure a uniformly high quality. Indeed, the accuracy of results reported here likely surpasses that in most experimental determinations. In addition, equilibrium energy minimization has calibrated following standard models ab initio theory: Hartree–Fock, MP2, CCSD,...
A systematic investigation has been carried out of the accuracy molecular equilibrium structures 19 small closed-shell molecules containing first-row atoms as predicted by following standard electronic ab initio models: Hartree–Fock (HF) theory, Mo/ller–Plesset theory to second, third, and fourth orders (MP2, MP3, MP4), coupled-cluster singles doubles (CCSD) theory; CCSD with perturbational triples corrections [CCSD(T)], configuration-interaction (CISD) model. For all models, calculations...
Using a valence double-zeta polarization basis, full configuration–interaction (FCI) calculations are carried out on water at its equilibrium geometry and geometries where the OH bond lengths stretched until dissociation. At same with basis set configuration interaction excitation levels up to hextuples, multireference singles doubles calculations, coupled cluster quadruples, Mo/ller–Plesset perturbation theory through order fifteen, complete active space second-order also out. The static...
A detailed study is carried out of the accuracy molecular equilibrium geometries obtained from least-squares fits involving experimental rotational constants B0 and sums ab initio vibration–rotation interaction αrB. The have been calculated for 18 single-configuration dominated molecules containing hydrogen first-row atoms at various standard levels theory. Comparisons with data tests internal consistency calculations show that structures generated using Hartree–Fock an similar to by a...
Individual orbital optimization of wave functions for the initial and final states produces most accurate given expansions, but complicates calculation transition-matrix elements since two sets orbitals will be nonorthogonal. The can transformed to become biorthonormal, in which case evaluation any matrix element proceed as orthonormal case. transformation wave-function expansion new basis imposes certain requirements on function, depending type transformation. An efficient general method...
Ab initio calculations of Raman differential intensities are presented at the self-consistent field (SCF) level theory. The electric dipole–electric dipole, dipole–magnetic dipole and quadrupole polarizability tensors calculated frequency incident light, using SCF linear response London atomic orbitals employed, imposing gauge origin invariance on calculations. Calculations have been carried out in harmonic approximation for CFHDT methyloxirane.
The accuracy of standard ab initio wave-function calculations atomization energies and reaction enthalpies has been assessed by comparing with experimental data for 16 small closed-shell molecules 13 isogyric reactions. investigated models are Hartree–Fock (HF), Møller–Plesset second-order perturbation theory (MP2), coupled-cluster singles doubles excitations (CCSD) CCSD perturbative triple-excitation corrections [CCSD(T)]; the one-electron basis sets used correlation-consistent cc-pVxZ...
It is shown that large scale MCSCF linear response (MCLR) calculations can be carried out efficiently using an iterative algorithm where the transformations are directly, i.e., without explicitly constructing MCLR matrices. Calculations presented on H2O of frequency dependent polarizabilities with configuration spaces containing up to 128 283 determinants.
Abstract Quantum chemical methods for the calculation of molecular properties to accuracy are reviewed. We begin by reviewing wave‐function based electronic structure theory, with emphasis on coupled‐cluster theory and description electron correlation in terms virtual excitations from occupied orbitals. Next, we discuss expansion orbitals atomic design one‐electron basis sets correlated calculations at level theory. In particular, convergence energy principal as realized...
The highly accurate calculation of molecular electronic structure requires the expansion wavefunction to be as nearly complete possible both in one- and n-electron space. In this review, we consider convergence behaviour computed energies, particular enthalpies reaction, a function one-electron Based on behaviour, extrapolations limit basis are such compared with direct computation energies near basis-set by means explicitly correlated methods. most elaborate computations put into...
The barriers of internal rotation the two phenyl groups in biphenyl are investigated using a combination coupled cluster and density functional theory. experimental for first time accurately reproduced; our best estimates 8.0 8.3 kJ/mol around planar perpendicular conformations, respectively. use flexible basis sets at least augmented quadruple-ζ quality is shown to be crucial prerequisite. Further, finally reconcile theory with experiment, extrapolations both set toward limit electron...
We describe an efficient implementation of the quadratic response function for a multiconfiguration self-consistent field reference wave function. The determines hyperpolarizability and its residues determine two-photon transition matrix elements between excited states. report sample calculations Ne H2.
A general coupled cluster method that allows arbitrary excitations from a single reference-determinant is proposed and tested. The based on generalization of the formalism spin-strings provides unified for storage manipulation operators. An initial implementation discussed used to study convergence hierarchy H2O CH2 at equilibrium geometry, employing up eightfold excitations. energy wave function contributions various excitation levels are examined. dissociation curve HF also studied. Using...
Abstract The CASSCF method of Roos and coworkers is reviewed compared to other approaches. It argued that the implementation marks beginning large scale multiconfigurational self consistent field calculations thus has been important in many fields molecular sciences. further related approaches will continue play an role development a understanding structures processes science, as these constitute appropriate starting point for wave function descriptions molecules complexes containing...