scholarly journals Theoretical and Experimental Insights into the Tandem Mannich—Electrophilic Amination Reaction: Synthesis of Safirinium Dyes

2021 ◽  
Vol 11 (12) ◽  
pp. 5498
Author(s):  
Jarosław Sączewski ◽  
Joanna Fedorowicz ◽  
Paulina Wiśniewska ◽  
Maria Gdaniec
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Secondary Amines ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Electrophilic Amination ◽  
Iminium Salts ◽  
Iminium Salt ◽  
Amination Reaction ◽  
Pcm Model

Isoxazolo[3,4-b]pyridin-3(1H)-ones are ‘spring-loaded’ compounds that quantitatively react with iminium salts derived from formaldehyde and secondary amines to yield fluorescent Safirinium dyes. The mechanism and energetics of the above tandem Mannich–electrophilic amination reaction have been investigated experimentally and using theoretical methods. The hybrid B3LYP functional with GD3 empirical dispersion and range-separated hybrid functional ωB97XD, both combined with a PCM model, were applied to acquire the energetic profiles of the studied reaction with respect to the structure of secondary amine and isoxazolone used. Diastereoselectivity of the tandem reactions involving iminium salt derived from L-proline has been rationalized theoretically by means of density functional theory calculations.

scholarly journals Exact Generalized Kohn-Sham Theory for Hybrid Functionals

2019 ◽  
Author(s):  
Rachel Garrick ◽  
Amir Natan ◽  
Tim Gould ◽  
Leeor Kronik
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
State Density ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Hybrid Functionals ◽  
The Many ◽  
Ground State Density ◽  
Equivalent Description

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; line-height: 18.0px; font: 15.8px Helvetica; color: #000000; -webkit-text-stroke: #000000; background-color: #ffffff} span.s1 {font-kerning: none} span.s2 {font-kerning: none; color: #000000} <p>Hybrid functionals have proven to be of immense practical value in density functional theory calculations. While they are often thought to be a heuristic construct, it has been established that this is in fact not the case. Here, we present a rigorous and formally exact generalized Kohn-Sham (GKS) density functional theory of hybrid functionals, in which exact remainder exchange-correlation potentials combine with a fraction of Fock exchange to produce the correct ground state density. Specifically, we generalize the well-known adiabatic con- nection theorem to the case of exact hybrid functional theory and use it to provide a rigorous distinction between multiplicative exchange and correlation components. We examine the exact theory by inverting reference electron densities to obtain exact GKS potentials for hybrid functionals, showing that an equivalent description of the many-electron problem is obtained with any arbitrary global fraction of Fock exchange. We establish the dependence of these exact components on the fraction of Fock exchange and use the observed trends to shed new light on the results of approximate hybrid functional calculations.</p>

scholarly journals Exact Generalized Kohn-Sham Theory for Hybrid Functionals

2020 ◽  
Author(s):  
Rachel Garrick ◽  
Amir Natan ◽  
Tim Gould ◽  
Leeor Kronik
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Formal Theory ◽  
Density Functional Theory Calculations ◽  
State Density ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Hybrid Functionals ◽  
The Many

Hybrid functionals have proven to be of immense practical value in density functional theory calculations. While they are often thought to be a heuristic construct, it has been established that this is in fact not the case. Here, we present a rigorous and formally exact analysis of generalized Kohn-Sham (GKS) density functional theory of hybrid functionals, in which exact remainder exchange-correlation potentials combine with a fraction of Fock exchange to produce the correct ground state density. First, we extend formal GKS theory by proving a generalized adiabatic connection theorem. We then use this extension to derive two different definitions for a rigorous distinction between multiplicative exchange and correlation components - one new and one previously postulated. We examine their density-scaling behavior and discuss their similarities and differences. We then present a new algorithm for obtaining exact GKS potentials by inversion of accurate reference electron densities and employ this algorithm to obtain exact potentials for simple atoms and ions. We establish that an equivalent description of the many-electron problem is indeed obtained with any arbitrary global fraction of Fock exchange and we rationalize the Fock-fraction dependence of the computed remainder exchange-correlation potentials in terms of the new formal theory. Finally, we use the exact theoretical framework and numerical results to shed light on the exchange-correlation potential used in approximate hybrid functional calculations and to assess the consequences of different choices of fractional exchange.<br><br>

scholarly journals Hybrid Density Functional Study of Au2Cs2I6, Ag2GeBaS4, Ag2ZnSnS4, and AgCuPO4 for the Intermediate Band Solar Cells

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3457 ◽  
Author(s):  
Murugesan Rasukkannu ◽  
Dhayalan Velauthapillai ◽  
Ponniah Vajeeston
Keyword(s):  
Density Functional ◽  
Mechanical Stability ◽  
Density Functional Theory Calculations ◽  
Functional Study ◽  
Photovoltaic Devices ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Intermediate Band ◽  
Intermediate Band Solar Cells ◽  
Hybrid Density Functional

We present a comprehensive investigation of the structural, electronic, mechanical, and optical properties of four promising candidates, namely Au2Cs2I6, Ag2GeBaS4, Ag2ZnSnS4, and AgCuPO4, for application in photovoltaic devices based on intermediate band (IB) cells. We perform accurate density functional theory calculations by employing the hybrid functional of Heyd, Scuseria, and Erhzerhof (HSE06). Calculations reveal that IBs are present in all proposed compounds at unoccupied states in the range of 0.34–2.19 eV from the Fermi level. The structural and mechanical stability of these four materials are also systematically investigated. Additional peaks are present in the optical spectra of these compounds, as characterised by a broadened energy range and high intensity for light absorption. Our findings, as reported in this work, may provide a substantial breakthrough on the understanding of these materials, and thus help the design of more efficient IB solar devices.

scholarly journals A band-gap database for semiconducting inorganic materials calculated with hybrid functional

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Sangtae Kim ◽  
Miso Lee ◽  
Changho Hong ◽  
Youngchae Yoon ◽  
Hyungmin An ◽  
...  
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Magnetic Ordering ◽  
Density Functional Theory Calculations ◽  
Inorganic Materials ◽  
Band Gaps ◽  
Device Performance ◽  
Photovoltaic Devices ◽  
Hybrid Functional ◽  
Functional Theory

Abstract Semiconducting inorganic materials with band gaps ranging between 0 and 5 eV constitute major components in electronic, optoelectronic and photovoltaic devices. Since the band gap is a primary material property that affects the device performance, large band-gap databases are useful in selecting optimal materials in each application. While there exist several band-gap databases that are theoretically compiled by density-functional-theory calculations, they suffer from computational limitations such as band-gap underestimation and metastable magnetism. In this data descriptor, we present a computational database of band gaps for 10,481 materials compiled by applying a hybrid functional and considering the stable magnetic ordering. For benchmark materials, the root-mean-square error in reference to experimental data is 0.36 eV, significantly smaller than 0.75–1.05 eV in the existing databases. Furthermore, we identify many small-gap materials that are misclassified as metals in other databases. By providing accurate band gaps, the present database will be useful in screening materials in diverse applications.

THERMOCHEMICAL PROPERTIES OF THE THIOCARBONYLTHIO COMPOUNDS FROM CONVENTIONAL DENSITY FUNCTIONAL THEORY CALCULATIONS

2010 ◽  
Vol 09 (supp01) ◽  
pp. 201-217
Author(s):  
ZHI-HUI ZHANG ◽  
TAO GAO ◽  
XIAO-FENG TIAN ◽  
NA HE
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Theoretical Data ◽  
Density Functional Theory Calculations ◽  
Good Method ◽  
Free Energies ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Reversible Addition

Density functional theory (DFT) calculations employed at two levels, B3LYP/6-31G+(d) and B3P86/6-31G+(d), are reported for the geometry, enthalpy, and free energy of reaction of a number of dithiobenzoate reversible addition fragmentation transfer (RAFT) reagents ( S=C(Ph)S–R , S=C(Z)S–CH2Ph ). Based on these theoretical data, the effectiveness of these RAFT reagents is analyzed. The conclusions, especially obtained at B3LYP/6-31G+(d) level, are in good agreement with the experimental results. Our calculations suggest that the dithiobenzoate ( S=C(Z)S–CH2Ph ), where Z is OC6H5 or N(alkyl)2 , is a poor RAFT reagent. Contrarily, the compound S=C(Ph)S–R , where R is C(Me)2Ph or C(Me)2CN , is a highly efficient RAFT reagent. Our results reveal the utility of the theoretical calculations of physical magnitudes for the rationalization of judging the effectiveness of RAFT reagents and demonstrated that DFT is a good method to calculate these data. In addition, our results on the enthalpies and Gibbs free energies of formation for the R radicals are calculated with the same method. These data are important for the design of logical and economical chemical process. Finally, the B3LYP hybrid functional is employed to predict the values of thermodynamic magnitudes for several new ithiobenzoates. Those results need to be verified by future experimental measurements or theoretical calculations.

scholarly journals Exact Generalized Kohn-Sham Theory for Hybrid Functionals

2020 ◽  
Author(s):  
Rachel Garrick ◽  
Amir Natan ◽  
Tim Gould ◽  
Leeor Kronik
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Formal Theory ◽  
Density Functional Theory Calculations ◽  
State Density ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Hybrid Functionals ◽  
The Many

Hybrid functionals have proven to be of immense practical value in density functional theory calculations. While they are often thought to be a heuristic construct, it has been established that this is in fact not the case. Here, we present a rigorous and formally exact analysis of generalized Kohn-Sham (GKS) density functional theory of hybrid functionals, in which exact remainder exchange-correlation potentials combine with a fraction of Fock exchange to produce the correct ground state density. First, we extend formal GKS theory by proving a generalized adiabatic connection theorem. We then use this extension to derive two different definitions for a rigorous distinction between multiplicative exchange and correlation components - one new and one previously postulated. We examine their density-scaling behavior and discuss their similarities and differences. We then present a new algorithm for obtaining exact GKS potentials by inversion of accurate reference electron densities and employ this algorithm to obtain exact potentials for simple atoms and ions. We establish that an equivalent description of the many-electron problem is indeed obtained with any arbitrary global fraction of Fock exchange and we rationalize the Fock-fraction dependence of the computed remainder exchange-correlation potentials in terms of the new formal theory. Finally, we use the exact theoretical framework and numerical results to shed light on the exchange-correlation potential used in approximate hybrid functional calculations and to assess the consequences of different choices of fractional exchange.<br><br>

scholarly journals Exact Generalized Kohn-Sham Theory for Hybrid Functionals

2020 ◽  
Author(s):  
Rachel Garrick ◽  
Amir Natan ◽  
Tim Gould ◽  
Leeor Kronik
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Formal Theory ◽  
Density Functional Theory Calculations ◽  
State Density ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Hybrid Functionals ◽  
The Many

<div>Hybrid functionals have proven to be of immense practical value in density functional theory calculations.</div><div>While they are often thought to be a heuristic construct, it has been established that this is in fact not the</div><div>case. Here, we present a rigorous and formally exact generalized Kohn-Sham (GKS) density functional theory</div><div>of hybrid functionals, in which exact remainder exchange-correlation potentials combine with a fraction of</div><div>Fock exchange to produce the correct ground state density. First, we extend formal GKS theory by proving a</div><div>generalized adiabatic connection theorem. We then use this extension to derive two different definitions for a</div><div>rigorous distinction between multiplicative exchange and correlation components - one new and one previously</div><div>postulated. We examine their density-scaling behavior and discuss their similarities and differences. We then</div><div>present a new algorithm for obtaining exact GKS potentials by inversion of accurate reference electron densities</div><div>and employ this algorithm to obtain exact potentials for simple atoms and ions. We establish that an equivalent</div><div>description of the many-electron problem is indeed obtained with any arbitrary global fraction of Fock exchange</div><div>and we rationalize the Fock-fraction dependence of the computed remainder exchange-correlation potentials in</div><div>terms of the new formal theory. Finally, we use the exact theoretical framework and numerical results to shed</div><div>light on the exchange-correlation potential used in approximate hybrid functional calculations and to assess the</div><div>consequences of different choices of fractional exchange.</div>

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