A5034879764- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Photochemistry and Electron Transfer Studies
- Nonlinear Optical Materials Research
- Molecular spectroscopy and chirality
- Molecular Junctions and Nanostructures
- Nonlinear Optical Materials Studies
- Synthesis and Properties of Aromatic Compounds
- X-ray Spectroscopy and Fluorescence Analysis
- Porphyrin and Phthalocyanine Chemistry
- DNA and Nucleic Acid Chemistry
- Photochromic and Fluorescence Chemistry
- Fullerene Chemistry and Applications
- Supramolecular Self-Assembly in Materials
- Solid-state spectroscopy and crystallography
- X-ray Diffraction in Crystallography
- Photoreceptor and optogenetics research
- Advanced NMR Techniques and Applications
- Atmospheric Ozone and Climate
- Various Chemistry Research Topics
- Spectroscopy and Laser Applications
- Luminescence and Fluorescent Materials
- Computational Drug Discovery Methods
- Crystallization and Solubility Studies
- Protein Structure and Dynamics
KTH Royal Institute of Technology
2016-2025
Kingston General Hospital
2024
Queen's University
2023
AlbaNova
2004-2022
Stockholm University
2020-2022
SLAC National Accelerator Laboratory
2022
Korea Advanced Institute of Science and Technology
2020-2021
Pohang University of Science and Technology
2021
Heidelberg University
2020-2021
Technical University of Denmark
2020-2021
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...
The electronic and vibronic contributions to the two-photon absorption of a series molecules with multi-branched structures have been studied using ab initio response theory. results indicate that coupling between different branches alone cannot explain experimental finding strong enhancement cross section over single branch structure, whereas it is predicted can play an important role in this respect. It shown for use circularly polarized light increase by factor 1.5 linearly excitation.
The linear response function has been derived and implemented in the time-dependent self-consistent field multiconfigurational approximations with consideration made for finite lifetimes of electronically excited states. Inclusion damping terms makes convergent at all frequencies including near-resonances resonances. Applications are calculations electric dipole polarizabilities hydrogen fluoride, methane, trans-butadiene, three push–pull systems. polarizability is complex a real part...
Based on the Ehrenfest theorem, an equation of motion that takes relaxation into account has been presented in wave-function theory, and resulting response functions are nondivergent off-resonant as well resonant regions optical frequencies. The derivation includes single- multideterminant reference states. When applied to electric dipole properties, correspond phenomenological sum-over-states expressions Orr Ward [Mol. Phys. 20, 513 (1971)] for polarizabilities hyperpolarizabilities...
Based on an asymmetric Lanczos-chain subspace algorithm, damped coupled cluster linear response functions have been implemented for the hierarchy of (CC) models including CC with single excitations (CCS), CC2, and double (CCSD), CCSD noniterative triple corrected excitation energies CCSDR(3). This work is a first step toward extension these theoretical electronic structure methods well-established high accuracy in UV-vis absorption spectroscopies to applications concerned x-ray radiation....
The development of electronic response theory in quantum chemistry has been reviewed, starting from the early 1970's and reaching current state-of-the-art. general applied to calculation a large number spectroscopic parameters over years, it implemented for majority standard structure methods. Two formulations theory, Ehrenfest expectation value quasi-energy derivative formulation, have turned into leading alternatives derivation computationally tractable expressions functions, they are here...
We present an implementation of the damped coupled-cluster linear response function based on asymmetric Lanczos chain algorithm for hierarchy approximations CCS (coupled-cluster singles), CC2 singles and approximate doubles), CCSD doubles). Triple corrections to excitation energies can be included via CCSDR(3) doubles with noniterative-triples-corrected energies) approximation. The performance some potentialities approach are investigated in calculations visible/ultraviolet absorption...
The Dalton Project provides a uniform platform access to the underlying full-fledged quantum chemistry codes and LSDalton as well PyFraME package for automatized fragmentation parameterization of complex molecular environments. is written in Python defines means library communication interaction. Intermediate data such integrals are exposed made accessible user form NumPy arrays, resulting extracted, analyzed, visualized. Complex computational protocols that may, instance, arise due need...
In this Letter, we present a pioneering analysis of the density functional approximations (DFAs) beyond generalized gradient approximation (GGA) for predicting two-photon absorption (2PA) strengths set push–pull π-conjugated molecules. more detail, have employed variety meta-generalized (meta-GGA) functionals, including SCAN, MN15, and M06-2X, to assess their accuracy in describing 2PA properties chosen 48 organic Analytic quadratic response theory is these performance compared against...
Solvent-induced two-photon absorption cross sections are calculated for a push−pull molecule in solutions using both self-consistent reaction field and internal finite approaches. It is shown analytically numerically that the results from two methods can be connected through induced local factors. The of studied polyene found to rather insensitive choice cavity shape. solvent dependence displays pattern different first hyperpolarizability.
A polarization propagator for x-ray spectra is outlined and implemented in density functional theory. It rests on a formulation of resonant-convergent first-order approach which makes it possible to directly calculate the absorption cross section at particular frequency without explicitly addressing excited states. The quality predicted spectrum relates only type applied any separate treatment dynamical relaxation effects.
By replacing the central thiophene unit of an anionic pentameric oligothiophene with other heterocyclic moities, a palette thiophene-based ligands distinct fluorescent properties were synthesized. All displayed superior selectivity towards recombinant amyloid fibrils as well disease-associated protein aggregates in tissue sections.
Abstract An open‐source program named VeloxChem has been developed for the calculation of electronic real and complex linear response functions at levels Hartree–Fock Kohn–Sham density functional theories. With an object‐oriented structure written in a Python/C++ layered fashion, enables time‐efficient prototyping novel scientific approaches without sacrificing computational efficiency, so that molecular systems involving up to beyond 500 second‐row atoms (or some 10,000 contracted part...
The performance of several standard and popular approaches for calculating X-ray absorption spectra at the carbon, nitrogen, oxygen K-edges 40 primarily organic molecules up to size guanine has been evaluated, focusing on low-energy intense 1s → π* transitions. Using results obtained with CVS-ADC(2)-x fc-CVS-EOM-CCSD as benchmark references, we investigate CC2, ADC(2), ADC(3/2), commonly adopted density functional theory (DFT)-based approaches. Here, focus is precision rather than accuracy...
Cubic response functions and various related residues are derived for multiconfigurational self-consistent field reference states. Compact computable expressions given which render the possibility to simultaneously consider several types of electric magnetic properties referring ground excited states multiphoton spectra between or different The perturbational expression excited-ground state difference in a frequency dependent property can be identified from double residue cubic function, one...
A formulation and implementation of the quadratic response function in adiabatic four-component Kohn-Sham approximation is presented. The noninteracting reference state time-reversal symmetric formed from Kramers pair spinors, energy density gradient corrected. Example calculations are presented for optical properties disubstituted halobenzenes their meta ortho conformations. It demonstrated that correlation relativistic effects not additive, it shown relativity alone reduces mubeta-response...
The response equations as occurring in the Hartree–Fock, multiconfigurational self-consistent field, and Kohn–Sham density functional theory have identical matrix structures. algorithms that are used for solving these discussed, new proposed where trial vectors split into symmetric antisymmetric components. Numerical examples given to compare performance of algorithms. calculations show standard equation frequencies smaller than highest occupied molecular orbital–lowest unoccupied orbital...
Near carbon K-edge X-ray absorption fine structure spectra of a series fluorine-substituted ethenes and acetone have been studied using coupled cluster density functional theory (DFT) polarization propagator methods, as well the static-exchange (STEX) approach. With complex (CPP) implemented in theory, relaxation effects following excitation core electrons are accounted for terms electron correlation, enabling systematic convergence these with respect to excitations operator. Coupled results...
We present a formulation of molecular response theory for the description quantum mechanical system in presence weak, monochromatic, linearly polarized electromagnetic field without introducing truncated multipolar expansions. The presentation focuses on linear absorption by adopting energy-loss approach combination with complex polarization propagator theory. Going beyond electric-dipole approximation is essential whenever studying electric-dipole-forbidden transitions, and general,...
We present a reduced-space algorithm for solving the complex (damped) linear response equations required to compute function hierarchy of methods: coupled cluster singles, singles and iterative approximate doubles, doubles. The solver is keystone element development damped methods nonlinear effects in resonant frequency regions.