ChemInform Abstract: Predicting Accurate Absolute Binding Energies in Aqueous Solution: Thermodynamic Considerations for Electronic Structure Methods

ChemInform ◽  
2015 ◽  
Vol 46 (26) ◽  
pp. no-no
Author(s):  
Jan H. Jensen
Keyword(s):  
Aqueous Solution ◽  
Electronic Structure ◽  
Binding Energies ◽  
Electronic Structure Methods

Performance of Electronic Structure Methods for the Description of Hückel-Möbius Interconversions in Extended π-Systems

2019 ◽  
Author(s):  
Tatiana Woller ◽  
Ambar Banerjee ◽  
Nitai Sylvetsky ◽  
Xavier Deraet ◽  
Frank De Proft ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Basis Set ◽  
Dft Methods ◽  
Molecular Switching ◽  
Wide Range ◽  
Electronic Structure Methods ◽  
Explicitly Correlated ◽  
Relative Errors ◽  
The Stability ◽  
Basis Set Expansion

<p>Expanded porphyrins provide a versatile route to molecular switching devices due to their ability to shift between several π-conjugation topologies encoding distinct properties. Taking into account its size and huge conformational flexibility, DFT remains the workhorse for modeling such extended macrocycles. Nevertheless, the stability of Hückel and Möbius conformers depends on a complex interplay of different factors, such as hydrogen bonding, p···p stacking, steric effects, ring strain and electron delocalization. As a consequence, the selection of an exchange-correlation functional for describing the energy profile of topological switches is very difficult. For these reasons, we have examined the performance of a variety of wavefunction methods and density functionals for describing the thermochemistry and kinetics of topology interconversions across a wide range of macrocycles. Especially for hexa- and heptaphyrins, the Möbius structures have a pronouncedly stronger degree of static correlation than the Hückel and figure-eight structures, and as a result the relative energies of singly-twisted structures are a challenging test for electronic structure methods. Comparison of limited orbital space full CI calculations with CCSD(T) calculations within the same active spaces shows that post-CCSD(T) correlation contributions to relative energies are very minor. At the same time, relative energies are weakly sensitive to further basis set expansion, as proven by the minor energy differences between MP2/cc-pVDZ and explicitly correlated MP2-F12/cc-pVDZ-F12 calculations. Hence, our CCSD(T) reference values are reasonably well-converged in both 1-particle and n-particle spaces. While conventional MP2 and MP3 yield very poor results, SCS-MP2 and particularly SOS-MP2 and SCS-MP3 agree to better than 1 kcal mol<sup>-1</sup> with the CCSD(T) relative energies. Regarding DFT methods, only M06-2X provides relative errors close to chemical accuracy with a RMSD of 1.2 kcal mol<sup>-1</sup>. While the original DSD-PBEP86 double hybrid performs fairly poorly for these extended p-systems, the errors drop down to 2 kcal mol<sup>-1</sup> for the revised revDSD-PBEP86-NL, again showing that same-spin MP2-like correlation has a detrimental impact on performance like the SOS-MP2 results. </p>

Ideal–Gas Thermochemical Properties for Alkanolamine and Related Species Involved in Carbon Capture Applications

2020 ◽  
Author(s):  
Nayyereh hatefi ◽  
William Smith
Keyword(s):  
Heat Capacity ◽  
Electronic Structure ◽  
Co2 Capture ◽  
Carbon Capture ◽  
Ideal Gas ◽  
Thermochemical Properties ◽  
Temperature Range ◽  
Comparison Results ◽  
Electronic Structure Methods ◽  
Protonated Forms

<div>Ideal{gas thermochemical properties (enthalpy, entropy, Gibbs energy, and heat capacity, Cp) of 49 alkanolamines potentially suitable for CO2 capture applications and their carbamate and protonated forms were calculated using two high{order electronic structure methods, G4 and G3B3 (or G3//B3LYP). We also calculate for comparison results from the commonly used B3LYP/aug-cc-pVTZ method. This data is useful for the construction of molecular{based thermodynamic models of CO2 capture processes involving these species. The Cp data for each species over the temperature range 200 K{1500 K is presented as functions of temperature in the form of NASA seven-term polynomial expressions, permitting the set of thermochemical properties to be calculated over this temperature range. The accuracy of the G3B3 and G4 results is estimated to be 1 kcal/mol and the B3LYP/aug-cc-pVTZ results are of nferior quality..</div>

Oxidation of ethylenediphosphinetetraacetate anions

1983 ◽  
Vol 48 (9) ◽  
pp. 2604-2608
Author(s):  
Jana Podlahová ◽  
Jaroslav Podlaha
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Electronic Structure ◽  
Acid Solutions ◽  
Tetraacetic Acid ◽  
Single Product ◽  
Weakly Acid ◽  
Inhibiting Effect ◽  
Oxidation By Molecular Oxygen ◽  
Protonated Forms

The oxidation of the ethylenediphosphinetetraacetate anion and its protonated forms by iodine, periodate, hydrogen peroxide, and oxygen has been studied in aqueous solution. The oxidation by the first three reagents is fast and yields a single product, bis(phosphine oxide), which has been isolated and characterized as ethylenebis(phosphinyl)tetraacetic acid. The oxidation by molecular oxygen proceeds considerably more slowly; in weakly acid solutions its rate is determined by the properties of the oxygen rather than by the electronic structure of the various protonated substrate species. The inhibiting effect of the phosphonium structures takes place only in strongly acid solutions.

scholarly journals Exploring the Franck-Condon region of a photoexcited charge transfer complex in solution to interpret femtosecond stimulated Raman spectroscopy: excited state electronic structure methods to unveil non-radiative pathways

2021 ◽  
Author(s):  
Federico Coppola ◽  
Paola Cimino ◽  
Umberto Raucci ◽  
Maria Gabriella Chiariello ◽  
Alessio Petrone ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Electronic Structure ◽  
Excited State ◽  
Charge Transfer ◽  
Charge Transfer Complex ◽  
Main Role ◽  
Photoinduced Charge Transfer ◽  
Electronic Structure Methods ◽  
Franck Condon ◽  
Photoinduced Charge

We present electronic structure methods to unveil non-radiative pathways of photoinduced charge transfer (CT) reactions that play a main role in photophysics and light harvesting technologies. A prototypical π-stacked molecular...

Nonadiabatic dynamics simulation of keto isocytosine: a comparison of dynamical performance of different electronic-structure methods

2017 ◽  
Vol 19 (29) ◽  
pp. 19168-19177 ◽  
Author(s):  
Deping Hu ◽  
Yan Fang Liu ◽  
Andrzej L. Sobolewski ◽  
Zhenggang Lan
Keyword(s):  
Electronic Structure ◽  
Dynamics Simulation ◽  
Nonadiabatic Dynamics ◽  
Electronic Structure Methods ◽  
Reaction Channels ◽  
Dynamics Simulations

Different reaction channels are obtained in the nonadiabatic dynamics simulations of isocytosine at CASSCF and ADC(2) levels.

scholarly journals Determination of the valence band edge of Fe oxide nanoparticles dispersed in aqueous solution through resonant photoelectron spectroscopy from a liquid microjet

2021 ◽  
Author(s):  
Giorgia Olivieri ◽  
Gregor Kladnik ◽  
Dean Cvetko ◽  
Matthew A. Brown
Keyword(s):  
Aqueous Solution ◽  
Electronic Structure ◽  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Band Edge ◽  
Photoemission Spectroscopy ◽  
Oxide Nanoparticles ◽  
Valence Band Edge ◽  
Resonant Photoemission

The electronic structure of hydrated nanoparticles can be unveiled by coupling a liquid microjet with a resonant photoemission spectroscopy.

First principles study of the structural, electronic and optical properties of crystalline o-phenanthroline

2016 ◽  
Vol 30 (14) ◽  
pp. 1650077 ◽  
Author(s):  
Hajar Nejatipour ◽  
Mehrdad Dadsetani
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Binding Energies ◽  
Many Body ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Independent Particle ◽  
Excitonic Effects ◽  
Comprehensive Study

In a comprehensive study, structural properties, electronic structure and optical response of crystalline o-phenanthroline were investigated. Our results show that in generalized gradient approximation (GGA) approximation, o-phenanthroline is a direct bandgap semiconductor of 2.60 eV. In the framework of many-body approach, by solving the Bethe–Salpeter equation (BSE), dielectric properties of crystalline o-phenanthroline were studied and compared with phenanthrene. Highly anisotropic components of the imaginary part of the macroscopic dielectric function in o-phenanthroline show four main excitonic features in the bandgap region. In comparison to phenanthrene, these excitons occur at lower energies. Due to smaller bond lengths originated from the polarity nature of bonds in presence of nitrogen atoms, denser packing, and therefore, a weaker screening effect, exciton binding energies in o-phenanthroline were found to be larger than those in phenanthrene. Our results showed that in comparison to the independent-particle picture, excitonic effects highly redistribute the oscillator strength.

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