scholarly journals Modeling the absorption spectrum of the permanganate ion in vacuum and in aqueous solution

2017 ◽  
Vol 19 (24) ◽  
pp. 15870-15875 ◽  
Author(s):  
Jógvan Magnus Haugaard Olsen ◽  
Erik Donovan Hedegård
Keyword(s):  
Aqueous Solution ◽  
Absorption Spectrum ◽  
Density Functional ◽  
Density Functional Theory Method ◽  
Functional Theory ◽  
Complete Active Space ◽  
Water Solvent ◽  
Solvent Models ◽  
Solvent Shift ◽  
Range Density

The absorption spectrum of MnO4− in vacuum and aqueous solution is modeled using the range-separated complete active space short-range density functional theory method (CAS-srDFT) combined with either implicit (PCM) or explicit (PE) solvent models. The experimental vacuum-to-water solvent shift of the lowest intense transition is reproduced by PE-CAS-srDFT.

scholarly journals TD-DFT/DFT study of Toluidine blue O in aqueous solution: vibronic transitions and electronic properties

2021 ◽  
Author(s):  
Lyudmila Kostjukova ◽  
Svetlana Leontieva ◽  
Victor Kostjukov
Keyword(s):  
Aqueous Solution ◽  
Absorption Spectrum ◽  
Toluidine Blue ◽  
Density Functional ◽  
Dipole Moments ◽  
Basis Set ◽  
Functional Theory ◽  
Solvent Models ◽  
Td Dft ◽  
Vibronic Transitions

The vibronic absorption spectrum of Toluidine blue O (TBO) dye in an aqueous solution was calculated using the time-dependent density functional theory (TD-DFT). The calculations were performed using all hybrid functionals supported by Gaussian16 software and 6-31++G(d,p) basis set with IEFPCM and SMD solvent models. The IEFPCM gave underestimated values of λmax in comparison with the experiment, what is a manifestation of the TD-DFT “cyanine failure”. However, the SMD made it possible to obtain good agreement between calculated and experimental spectra. The best fit was achieved using the X3LYP functional. The dipole moments and atomic charges of the ground and excited states of the TBO molecule were calculated. Photoexcitation leads to an increase in the dipole moment of the dye molecule. An insignificant photoinduced electron transfer was found in the central ring of the chromophore of the TBO molecule. Vibronic transitions play a significant role in the absorption spectrum of the dye.

scholarly journals Hole-Hole Tamm-Dancoff-Approximated Density Functional Theory: A Highly Efficient Electronic Structure Method Incorporating Dynamic and Static Correlation

2020 ◽  
Author(s):  
Christoph Bannwarth ◽  
Jimmy K. Yu ◽  
Edward G. Hohenstein ◽  
Todd J. Martínez
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Excited States ◽  
Density Functional ◽  
Random Phase ◽  
Density Functional Theory Method ◽  
Functional Theory ◽  
Complete Active Space ◽  
Dynamic Correlation ◽  
Static Correlation

<div> <div> <div> <p>The study of photochemical reaction dynamics requires accurate as well as computationally efficient electronic structure methods for the ground and excited states. While time-dependent density functional theory (TDDFT) is not able to capture static correlation, complete active space self-consistent field (CASSCF) methods are deficient in their ability to describe dynamic correlation. Hence, inexpensive methods that encompass both static and dynamic electron correlation effects are of high interest. Here, we describe the hole-hole Tamm- Dancoff approximated (<i>hh</i>-TDA) density functional theory method, which is closely related to the previously established particle-particle random phase approximation (<i>pp</i>-RPA) and its TDA variant (<i>pp</i>-TDA). In <i>hh</i>-TDA, the <i>N</i>-electron electronic states are obtained through double annihilations starting from a doubly anionic (<i>N</i>+2 electron) reference state. In this way, <i>hh</i>-TDA treats ground and excited states on equal footing, thus allowing for conical intersections to be correctly described. The treatment of dynamic correlation is introduced through the use of commonly-employed density functional approximations to the exchange-correlation potential. <i>hh</i>-TDA appears to be a promising candidate to efficiently treat the photochemistry of organic and biochemical systems that involve several low-lying excited states – particularly those with both low-lying pipi* and npi* states where inclusion of dynamic correlation is essential to describe the relative energetics. In contrast to the existing literature on <i>pp</i>-TDA, we employ a functional- dependent choice for the response kernel in <i>pp</i>- and <i>hh</i>-TDA, which closely resembles the response kernels occurring in linear response and collinear spin-flip TDDFT. </p> </div> </div> </div>

scholarly journals H2O coordination in macropa complexes of f elements (Ac, La, Lu): feasibility of the 11th coordination site

2021 ◽  
Author(s):  
Attila Kovács ◽  
Zoltán Varga
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Density Functional ◽  
Molecular Level ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Coordination Site ◽  
Additional Ligand ◽  
Ligand Coordination ◽  
Bonding Properties

AbstractThe feasibility of an additional ligand coordination at the 11th coordination site of actinium, lanthanum, and lutetium ions in 10-fold coordinated macropa complexes has been studied by means of density functional theory calculations. The study covered the two main macropa conformers, Δ(δλδ)(δλδ) and Δ(λδλ)(λδλ), favoured by larger (Ac3+, La3+) and smaller (Lu3+) ions, respectively. At the molecular level, the coordination of H2O is the most favourable to the largest Ac3+ while only slightly less to La3+. Protonation of the picoline arms enhances the coordination by shifting the metal ion closer to the open site of the ligand. The choice of macropa conformer has only a slight influence on the strength and bonding properties of the H2O coordination. Aqueous solution environment decreases considerably the energy gain of H2O coordination at the 11th coordination site.

Density Functional Theory Study of Uranium(VI) Aquo Chloro Complexes in Aqueous Solution

2008 ◽  
Vol 112 (11) ◽  
pp. 2428-2436 ◽  
Author(s):  
Michael Bühl ◽  
Nicolas Sieffert ◽  
Volodymyr Golubnychiy ◽  
Georges Wipff
Keyword(s):  
Aqueous Solution ◽  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Chloro Complexes

Study of the Stability and Chemical Reactivity of a Series of Tetrazole Pyrimidine Hybrids by the Density Functional Theory Method (DFT)

2021 ◽  
Vol 37 (4) ◽  
pp. 805-812
Author(s):  
Ahissandonatien Ehouman ◽  
Adjoumanirodrigue Kouakou ◽  
Fatogoma Diarrassouba ◽  
Hakim Abdel Aziz Ouattara ◽  
Paulin Marius Niamien
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Molecular Descriptors ◽  
Chemical Reactivity ◽  
Density Functional Theory Method ◽  
Functional Theory ◽  
Reactivity Descriptors ◽  
The Density Functional Theory ◽  
The Stability ◽  
Global Reactivity Descriptors

Our theoretical study of stability and reactivity was carried out on six (06) molecules of a series of pyrimidine tetrazole hybrids (PTH) substituted with H, F, Cl, Br, OCH3 and CH3 atoms and groups of atoms using the density function theory (DFT). Analysis of the thermodynamic formation quantities confirmed the formation and existence of the series of molecules studied. Quantum chemical calculations at the B3LYP / 6-311G (d, p) level of theory determined molecular descriptors. Global reactivity descriptors were also determined and analyzed. Thus, the results showed that the compound PTH_1 is the most stable, and PTH_5 is the most reactive and nucleophilic. Similarly, the compound PTH_4 is the most electrophilic. The analysis of the local descriptors and the boundary molecular orbitals allowed us to identify the preferred atoms for electrophilic and nucleophilic attacks.

scholarly journals Practical and Theoretical Study on the Inhibitory Influences of New Azomethine Derivatives Containing an 8-Hydroxyquinoline Moiety for the Corrosion of Carbon Steel in 1 M HCl

2018 ◽  
Vol 34 (6) ◽  
pp. 3016-3029 ◽  
Author(s):  
A. El-Yaktini ◽  
A. Lachiri ◽  
M. El-Faydy ◽  
F. Benhiba ◽  
H. Zarrok ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Density Functional ◽  
Electrochemical Impedance ◽  
Density Functional Theory Method ◽  
Steel Corrosion ◽  
Experimental Results ◽  
Chemical Parameters ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Inhibition Ability

The inhibition ability of a new Azomethine derivatives containing the 8-hydroxyquinoline (BDHQ and MDHQ) towards carbon steel corrosion in HCl solution was studied at various concentrations and temperatures using weight loss, polarization curves and electrochemical impedance spectroscopy (EIS) methods. The experimental results reveal that BDHQ and MDHQ are efficient mixed type corrosion inhibitors, and their inhibition efficiencies increase with increasing concentration. The adsorption of these inhibitors on mild steel surface obeys Langmuir isotherm. Quantum chemical parameters are calculated using the Density Functional Theory method (DFT) and Monte Carlo simulations. Correlation between theoretical and experimental results is discussed.

scholarly journals Supramolecular Complexes of Cucurbiturils with Second Group Metal Salts and Hydrates and Histamine

INEOS OPEN ◽  
2021 ◽  
Vol 4 ◽  
Author(s):  
Yu. A. Borisov ◽  
◽  
S. S. Kiselev ◽  
Keyword(s):  
Aqueous Solution ◽  
Density Functional Theory ◽  
Density Functional ◽  
Metal Salts ◽  
Supramolecular Complexes ◽  
Water Molecules ◽  
Functional Theory ◽  
Guest Molecules ◽  
First Time ◽  
Formation Energies

The interaction of cucurbiturils (Q6, Q7, and Q8) with Ca and Ba chlorides and iodides are studied for the first time by density functional theory. The thermodynamic parameters for the formation of host–guest complexes are calculated. The structures of complexes of Q6 and Q7 with one and two guest molecules are established. The energy parameters for the transfer of Be2+ and Ba2+ cations from an aqueous solution into the cavity of Q7 containing n water molecules are defined. The dependences of the formation energies for complexes Q7WnBe2+ and Q7WnBa2+ on the number of water molecules are shown to be parabolic, with the energy minima at n = 5 and n = 6, respectively. It is found that Q7 can form in an aqueous solution supramolecular complexes with protonated histamine (HA) and neutral histamine in the presence of Ca2+ ions.

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