A5084792214- Spectroscopy and Quantum Chemical Studies
- Photochemistry and Electron Transfer Studies
- Advanced NMR Techniques and Applications
- Solid-state spectroscopy and crystallography
- Molecular spectroscopy and chirality
- Advanced Chemical Physics Studies
- Ionic liquids properties and applications
- Electron Spin Resonance Studies
- Crystallography and molecular interactions
- Thermodynamic properties of mixtures
- Organic and Molecular Conductors Research
- Crystallization and Solubility Studies
- Advanced Battery Materials and Technologies
- Perovskite Materials and Applications
- Free Radicals and Antioxidants
- Electrochemical Analysis and Applications
- Molecular Spectroscopy and Structure
- Chemical Reaction Mechanisms
- Protein Interaction Studies and Fluorescence Analysis
- Chemical Synthesis and Characterization
- NMR spectroscopy and applications
- Chemical and Physical Properties in Aqueous Solutions
- DNA and Nucleic Acid Chemistry
- Thermal and Kinetic Analysis
- Nuclear Physics and Applications
Vilnius University
2014-2024
KTH Royal Institute of Technology
2010-2012
Ørsted (Denmark)
2005-2011
University of Copenhagen
2005-2011
Polish Academy of Sciences
2010
University of Southern Denmark
2009-2010
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 theory and implementation of an advanced quantum mechanics/molecular mechanics (QM/MM) approach using a fully self-consistent polarizable embedding (PE) scheme. It is layered model designed for effective yet accurate inclusion anisotropic medium in mechanical calculation. The potential described by atomistic representation including terms up to localized octupoles polarizabilities. generally applicable any chemical description but here implemented the case Kohn−Sham density...
We present the theory and an implementation of combined quantum mechanics/molecular mechanics/polarizable dielectric continuum (QM/MM/PCM) method. This is a fully polarizable layered model designed for effective inclusion medium in quantum-mechanical calculation. The short-range part solvent electrostatic potential described by atomistic while long-range this continuum. QM/MM/PCM method has been implemented combination with QM linear response techniques allowing assessment of, e.g., vertical...
The combined linear response coupled cluster/molecular mechanics (CC/MM) scheme including mutual polarization effects in the coupling Hamiltonian is applied together with supermolecular CC methods to study of gas-to-aqueous solution blue shift n --> pi* excitation energy acetone. aug-cc-pVDZ basis set found be adequate for calculation this energy. In condensed phase, obtained by statistical averaging over 800 solute-solvent configurations extracted from a molecular dynamics simulation. We...
The performance of the Hartree-Fock method and three density functionals B3LYP, PBE0, CAM-B3LYP is compared to results based on coupled cluster singles doubles model in predictions solvatochromic effects vertical n-->pi* pi-->pi* electronic excitation energies acrolein. All structure methods employed same solvent model, which combined quantum mechanics/molecular mechanics approach together with a dynamical averaging scheme. In addition predicted effects, we have also performed spectroscopic...
Uracil is a commonly occurring pyrimidine derivative found in RNA where it base pairs with adenine. Rationalizing the electronic properties of uracil both gas phase and aqueous solution fundamental importance because significant biological role played by this molecule. This paper presents accurate predictions solvatochromic shifts lowest π → π* n vertical excitation energies due to an solution. The calculations are conducted using recently developed combined quantum mechanics/molecular...
The dimethylamino nitro stilbene (DANS) molecule is studied for exploring solvent effects on two-photon absorption using the quantum mechanical/molecular mechanical (QM/MM) response theory approach, where part represented by density functional theory. We have explored role of geometrical change chromophore in solution, importance taking a dynamical average over sampled structures and granular representation polarization electrostatic interactions with classically described medium. line shape...
The gas-to-aqueous solution shifts of the 17O and 13C NMR isotropic shielding constants for carbonyl chromophore in formaldehyde acetone are investigated. For condensed-phase problem, we use hybrid density functional theory/molecular mechanics approach combination with a statistical averaging over an appropriate number solute-solvent configurations extracted from classical molecular dynamics simulations. PBE0 exchange-correlation 6-311++G(2d,2p) basis set used calculation constants. London...
We have performed Car−Parrinello mixed quantum mechanics/molecular mechanics (CP-QM/MM) calculations for stilbazolium merocyanine (SM) in polar and nonpolar solvents order to explore the role of solute molecular geometry, solvation shell structure, different interaction mechanisms on absorption spectra its dependence solvent polarity. On basis average bond length values group charge distributions, we find that SM molecule remains a neutral quinonoid form chloroform (a solvent) while it...
We present the first systematic investigation of shifts in nuclear magnetic resonance (NMR) shielding constant due to hydrogen bonding using either series wave function based methods, Hartree−Fock (HF), second-order Møller-Plesset perturbation theory (MP2), Coupled Cluster Singles and Doubles (CCSD) CCSD extended with an approximate description triples (CCSD(T)), or Density Functional Theory (DFT) employing B3LYP, PBE0, KT3 exchange correlation (xc) functionals. The molecular systems...
We present theory and implementation of calculation spin-spin coupling constants within combined quantum mechanics/molecular mechanics methods. Special attention is given to the role explicit solvent polarization as well molecular consequences due hydrogen bonding. The model generally applicable but here implemented for case density functional theory. First applications liquid water acetylene in aqueous solution are presented. Good agreement between experiment obtained both cases, thereby...
Resonant inelastic x-ray scattering spectra excited at the $O1{s}^{\ensuremath{-}1}{\ensuremath{\pi}}^{*}$ resonance of liquid acetone are presented. Scattering to electronic ground state shows a resolved vibrational progression where dominant contribution is due C-O stretching mode, thus demonstrating unique sensitivity method local potential energy surface in complex molecular systems. For electronically states, soft modes and, smaller extent, intermolecular interactions give broadening,...
Motivated by future possibilities to design target molecules for fibrils with diagnostic or therapeutic capability related amyloidosis diseases, we investigate in this work the dielectric nature of amyloid fibril microenvironments different binding sites using an optical probe, thioflavin-T (THT), which has been used extensively stain such fibrils. We study fibril-environment-induced structural and spectral changes THT at each site compare results fibril-free situation aqueous solution. All...
Methyl groups are ubiquitous in synthetic materials and biomolecules. At sufficiently low temperature, they behave as quantum rotors populate only the rotational ground state. In a symmetric potential, three localized substates degenerate become mixed by tunnel overlap to delocalized states separated splitting ν t . Although can be inferred several techniques, coherent superposition of tunnel-split direct measurement have proven elusive. Here, we show that nearby electron spin provides...
First comprehensive EPR study of Mn 2+ ion incorporation in lead halide hybrid perovskites. We use these ions as local probes to the structural and dynamic properties MAPbCl 3 .
(1)H, (13)C, and (81)Br NMR spectra of the neat room-temperature ionic liquid (RTIL), namely, 1-decyl-3-methyl-imidazolium bromide ([C(10)mim][Br]) as well its solutions in acetonitrile, dichloromethane, methanol, water have been investigated. The most important observation present work is significant broadening signal [C(10)mim][Br] organic solvents, which molecules tend to associate into hydrogen bond networks appearance complex contour RTIL crystalline (LC) ionogel formed RTIL/water...
The H/D exchange process in the imidazolium-based room temperature ionic liquids (RTILs) 1-decyl-3-methyl-imidazolium bromide- and chloride ([C10mim][Br] [C10mim][Cl]) D2O solutions of various concentrations was studied applying (1)H, (13)C NMR, Raman spectroscopy. time dependencies integral intensities NMR spectra indicate that [C10mim][Br] at very high dilution (10(-4) mole fraction RTIL) runs only slightly faster than [C10mim][Cl]. kinetics this drastically changes above critical...
We present a pulse electron paramagnetic resonance (EPR) and electron–nuclear double (ENDOR) study of manganese-doped [(CH3)2NH2][Zn(HCOO)3] dense metal–organic framework which exhibits structural phase transition at 163 K. The echo-detected field sweep Mn2+ EPR spectrum the low-temperature is in perfect agreement with previous continuous-wave results, while disordered reveals significant transition-dependent relaxation. 1H ENDOR pattern indicates several protons vicinity ion. experimental...
In this work the role of higher molecular aggregation in proton transfer processes within hydrogen bond (H-bond) is investigated. The H-bonded complex consisting 4-cyanopyridine (CyPy) with trichloroacetic acid (TCA) has been studied solutions acetonitrile, carbon tetrachloride, chloroform and dichloroethane as solvent by FTIR spectroscopy quantum chemical DFT calculations. order to illustrate effect increasing H-bond strength investigations have also performed on CyPy H(2)O, acetic-,...
The 15N NMR spectrum of adenine in aqueous solution has been modeled using high-level combined density functional theory/molecular mechanics techniques coupled to a dynamical averaging scheme. explicit consideration the three lowest-energy tautomers adenine—H9, H7 and H3—allows for well-founded comparison experimental data. Based on very good agreement between predicted measured adenine, we have estimated populations H9 be around 83 17%, respectively—in with data—and thus concluded that H3...
Abstract In this study, we have applied two different spanning protocols for obtaining the molecular conformations of L ‐tryptophan in aqueous solution, namely a dynamics simulation and mechanics conformational search with subsequent geometry re‐optimization stable conformers using quantum mechanically based method. These represent standard ways set on which NMR calculations may be performed. The results stemming from solute–solvent configurations extracted MD at 300 K are found to inferior...
A general density functional theory/molecular mechanics approach for computation of electronic g-tensors solvated molecules is presented. We apply the theory to commonly studied di-tert-butyl nitroxide molecule, simplest model compound spin labels, and explore role an aqueous environment various approximations its treatment. It found that successive improvements solvent shift g-tensor are obtained by going from polarizable continuum discrete models levels sophistication. The study shows...
The H-bonded complexes of pyridine N-oxide (PyO) with H(2)O, acetic, cyanoacetic, propiolic, tribromoacetic, trichloroacetic, trifluoroacetic, hydrochloric, and methanesulfonic acids have been studied by FTIR NMR spectroscopy, X-ray diffraction, quantum chemical DFT calculations. Correlations between vibrational frequencies the NO stretching PyO ring modes geometric parameters H-bond established. experiments show calculations confirm that definite discontinuity is present in vicinity...
The 23Na quadrupolar coupling constant of the Na+ ion in aqueous solution has been predicted using molecular dynamics simulations and hybrid quantum mechanics/molecular mechanics methods for calculation electric field gradients. developed computational approach is generally expected to provide reliable estimates constants monoatomic species condensed phases, we show here that intermolecular polarization non-electrostatic interactions are crucial importance as they result a 100% increased...