A5071652159- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Quantum, superfluid, helium dynamics
- Photochemistry and Electron Transfer Studies
- Molecular Junctions and Nanostructures
- Protein Structure and Dynamics
- Molecular spectroscopy and chirality
- Nonlinear Optical Materials Research
- Machine Learning in Materials Science
- X-ray Diffraction in Crystallography
- Solid-state spectroscopy and crystallography
- Atmospheric Ozone and Climate
- Advanced NMR Techniques and Applications
- Surface Chemistry and Catalysis
- Atmospheric chemistry and aerosols
- Porphyrin and Phthalocyanine Chemistry
- Free Radicals and Antioxidants
- Computational Drug Discovery Methods
- Quantum Dots Synthesis And Properties
- Rheumatoid Arthritis Research and Therapies
- Osteoarthritis Treatment and Mechanisms
- Inorganic Fluorides and Related Compounds
- nanoparticles nucleation surface interactions
- Theoretical and Computational Physics
- Spectroscopy and Laser Applications
American College of Rheumatology
2022
Aarhus University
2008-2019
John Wiley & Sons (United States)
2019
Oak Ridge National Laboratory
2019
Ecological Society of America
2019
IFC Research (United Kingdom)
2019
Auburn University
2019
The University of Texas at Austin
2016
Lundbeck Foundation
2008-2012
Lundbeck (Denmark)
2012
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 present the first binding energy benchmark set at CBS limit of strongly hydrogen bonded atmospheric molecular clusters.
We propose a reformulation of the traditional (T) triples correction to coupled cluster singles and doubles (CCSD) energy in terms local Hartree–Fock (HF) orbitals such that its structural form aligns with our recently developed linear-scaling divide–expand–consolidate (DEC) family correlation methods. In DEC-CCSD(T) calculation, basis occupied virtual HF is used partition correlated calculation on full system into number independent atomic fragment pair calculations, each performed within...
A general method is presented for the calculation of molecular properties to arbitrary order at Kohn–Sham density functional level theory. The quasienergy and Lagrangian formalisms are combined derive response functions their residues by straightforward differentiation derivative using elements matrix in atomic orbital representation as variational parameters. Response equations expressed basis, allowing recent advances field linear-scaling methodology be used. Time-dependent static...
We present a thorough locality analysis of the divide-expand-consolidate amplitude equations for second-order Møller-Plesset perturbation theory and coupled cluster singles doubles (CCSD) model, which demonstrates that are local when expressed in terms set occupied unoccupied Hartree-Fock orbitals, such as least-change molecular basis. The thus shows CC calculation on large system may be carried out calculations small orbital fragments total system, where sizes fragment spaces determined...
It is demonstrated that a set of local orthonormal Hartree-Fock (HF) molecular orbitals can be obtained for both the occupied and virtual orbital spaces by minimizing powers variance using trust-region algorithm. For power exponent equal to one, Boys localization function obtained. increasing exponents, penalty delocalized increased smaller maximum spreads are encountered. Calculations on superbenzene, C(60), fragment titin protein show outlier may These disappear when larger than one. small...
Previously, we have introduced the linear scaling coupled cluster (CC) divide-expand-consolidate (DEC) method, using an occupied space partitioning of standard correlation energy. In this article, show that energy may alternatively be expressed a virtual partitioning, and Lagrangian partitioned elements from both schemes. The partitionings leads to atomic site pair interaction energies which are term-wise invariant with respect orthogonal transformation among or orbitals. Evaluating local...
Divide-Expand-Consolidate (DEC) is a local correlation method where the inherent locality of electron problem used to express correlated calculation on large molecular system in terms small independent fragment calculations employing subsets HF orbitals. A crucial feature DEC scheme that sizes orbital spaces are determined black box manner during calculation. In this way it ensured energy has been predefined precision compared conventional present work we apply calculate as well density...
We present a quasienergy-based formulation of damped response theory where common effective lifetime parameter has been introduced for all excited states in terms complex excitation energies. The introduction finite state lifetimes leads to set (complex) equations, which have the same form orders perturbation. An algorithm is presented solving equations Hartree–Fock and Kohn–Sham density functional theory. use quasienergy allows us obtain directly computationally simplest expressions...
Quantum-mechanical embedding methods have in recent years gained significant interest and may now be applied to predict a wide range of molecular properties calculated at different levels theory. To reach high level accuracy methods, both the electronic structure model active region potential need sufficiently quality. In fact, failures quantum mechanics/molecular mechanics (QM/MM)-based often been associated with QM/MM methodology itself; however, many cases reason for such is due use an...
The Resolution of the Identity second-order Møller-Plesset perturbation theory (RI-MP2) method is implemented within linear-scaling Divide-Expand-Consolidate (DEC) framework. In a DEC calculation, full molecular correlated calculation replaced by set independent fragment calculations each using subset total orbital space. number scales linearly with system size, rendering and massively parallel. DEC-RI-MP2 can be viewed as an approximation to DEC-MP2 where RI utilized in calculation....
We show that standard density functional theory leads to large errors in the electron distribution compared reference second order Møller-Plesset perturbation (MP2) calculations for insulin molecule and zwitterionic peptides, while range-separated versions perform much better. The error is quantified terms of electrostatic potential (ESP) on a molecular surface, which shows incorrectly predicts partial transfer from anionic cationic sites. In addition, we compare MP2 calculated ESPs those...
Damped response theory is applied to the calculation of two-photon absorption (TPA) spectra, which are determined directly, at each frequency, from a modified damped cubic function. The TPA spectrum may therefore be evaluated for selected frequency ranges, making approach attractive calculations on large molecules with high density states, where using standard more problematic. can also case intermediate state resonances, expression divergent. Both exact and its application within functional...
For large molecular systems conventional implementations of second order Møller–Plesset (MP2) theory encounter a scaling wall, both memory- and time-wise. We describe how this wall can be removed. present massively parallel algorithm for calculating MP2 energies densities using the divide–expand–consolidate scheme where calculation on system is divided into many small fragment calculations employing local orbital spaces. The resulting linear-scaling with size, exhibits near perfect...
We present a local framework for the calculation of coupled cluster excitation energies large molecules (LoFEx). The method utilizes time-dependent Hartree-Fock information about transitions interest through concept natural transition orbitals (NTOs). NTOs are used in combination with localized occupied and virtual to generate reduced orbital space (XOS) specific each where standard is carried out. Each XOS optimized ensure that determined predefined precision. apply LoFEx RI-CC2 model...
Using the coupled cluster Lagrangian technique, we have determined perturbative corrections to singles and doubles (CCSD) energy that converge towards singles, doubles, triples (CCSDT) triples, quadruples (CCSDTQ) energies, considering CCSD state as unperturbed reference fluctuation potential perturbation. Since technique is utilized, satisfy Wigner's 2n + 1 rule for amplitudes 2 Lagrange multipliers. The define perturbation series, CCSD(T–n) CCSD(TQ–n), which are term-wise size extensive...
The Divide‐Expand‐Consolidate ( DEC ) scheme is a linear‐scaling and massively parallel framework for high accuracy coupled cluster CC calculations on large molecular systems. It designed as black‐box method, which ensures error control in the correlation energy properties. combined with implementation to fully utilize modern manycore architectures providing fast time solution. performance portability will straightforwardly benefit from new hardware developments. has been applied several...
We demonstrate that the divide-expand-consolidate (DEC) scheme--which has previously been used to determine second-order Møller-Plesset (MP2) correlation energy--can be applied evaluate MP2 molecular gradient in a linear-scaling and embarrassingly parallel manner using set of local Hartree-Fock orbitals. All manipulations four-index quantities (describing electron effects) are carried out small orbital fragment spaces, whereas two-index treated for full system. The sizes spaces determined...
We report an implementation of the molecular gradient using divide-expand-consolidate resolution identity second-order Møller-Plesset perturbation theory (DEC-RI-MP2). The new DEC-RI-MP2 method combines precision control as well linear-scaling and massively parallel features DEC scheme with efficient evaluations contributions RI approximation. further demonstrate that is capable calculating gradients for very large systems. A test set supramolecular complexes containing up to 158 atoms 1960...
A general method is presented for the efficient elimination of response parameters in molecular property calculations variational and nonvariational energies. For energies, Wigner's 2n+1 rule obtained as a special case more k(2n+1) rule, which states that subset k perturbations within total set z>or=k perturbations, may be eliminated according to (normally applied full perturbations). Nonvariational energies treated by introducing Lagrange multipliers satisfy stronger 2n+2 while...
The recently developed Local Framework for calculating Excitation energies (LoFEx) is extended to the coupled cluster singles and doubles (CCSD) model. In new scheme, a standard CCSD excitation energy calculation carried out within reduced orbital space (XOS), which composed of localised molecular orbitals natural transition determined from time-dependent Hartree–Fock theory. presented algorithm uses series second-order approximate (CC2) calculations optimise XOS in black-box manner. This...
We present a new framework for calculating coupled cluster (CC) excitation energies at reduced computational cost. It relies on correlated natural transition orbitals (NTOs), denoted CIS(D′)-NTOs, which are obtained by diagonalizing generalized hole and particle density matrices determined from configuration interaction singles (CIS) information additional terms that represent correlation effects. A transition-specific orbital space is based the eigenvalues of standard CC energy calculation...
The theoretical foundation for solving coupled cluster singles and doubles (CCSD) amplitude equations to a desired precision in terms of independent fragment calculations using restricted local orbital spaces is reinvestigated with focus on the individual error sources. Four different sources are identified theoretically numerically it demonstrated that, practical purposes, CCSD can be from at MP2 level. development establishes solid fragments, thus divide-expand-consolidate large molecular...