scholarly journals Assessment of density functional methods for exciton binding energies and related optoelectronic properties

RSC Advances ◽  
2015 ◽  
Vol 5 (123) ◽  
pp. 101370-101376 ◽  
Author(s):  
Jui-Che Lee ◽  
Jeng-Da Chai ◽  
Shiang-Tai Lin
Keyword(s):  
Binding Energy ◽  
Density Functional ◽  
Mean Absolute Error ◽  
Absolute Error ◽  
Binding Energies ◽  
Optoelectronic Properties ◽  
Exciton Binding Energy ◽  
Dft Methods ◽  
Density Functional Methods ◽  
Functional Methods

Mean absolute error (MAE) in exciton binding energy (Eb) from 9 DFT methods against benchmark CCSD and EOM-CCSD.

scholarly journals Substitution Effects on the Optoelectronic Properties of Coumarin Derivatives

2019 ◽  
Vol 10 (1) ◽  
pp. 144
Author(s):  
Amit Kumar ◽  
Roberto Baccoli ◽  
Antonella Fais ◽  
Alberto Cincotti ◽  
Luca Pilia ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Molecular Orbital ◽  
Density Functional ◽  
Optoelectronic Properties ◽  
Exciton Binding Energy ◽  
Basis Set ◽  
Substitution Effects ◽  
Coumarin Derivatives ◽  
Functional Theory

Coumarin derivatives have gathered major attention largely due to their versatile utility in a wide range of applications. In this framework, we report a comparative computational investigation on the optoelectronic properties of 3-phenylcoumarin and 3-heteroarylcoumarin derivatives established as enzyme inhibitors. Specifically, we concentrate on the variation in the optoelectronic characteristics for the hydroxyl group substitutions within the coumarin moiety. In order to realize our aims, all-electron density functional theory and time dependent density functional theory calculations were performed with a localized Gaussian basis-set matched with a hybrid exchange–correlation functionals. Molecular properties such as highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies, vertical ionization (IEV) and electron affinity energies, absorption spectra, quasi-particle gap, and exciton binding energy values are examined. Furthermore, the influence of solvent on the optical properties of the molecules is considered. We found a good agreement between the experimental (8.72 eV) and calculated (8.71 eV) IEV energy values for coumarin. The computed exciton binding energy of the investigated molecules indicated their potential optoelectronics application.

Switching the charge transfer characteristics of quaterthiophene from p-type to n-type via interactions with carbon nanotubes

2019 ◽  
Vol 21 (44) ◽  
pp. 24820-24827
Author(s):  
Ankita Joshi ◽  
C. N. Ramachandran
Keyword(s):  
Carbon Nanotubes ◽  
Charge Transfer ◽  
Charge Transport ◽  
Density Functional ◽  
Optoelectronic Properties ◽  
Density Functional Methods ◽  
Transfer Characteristics ◽  
Functional Methods ◽  
P Type

Using density functional methods, charge transport and optoelectronic properties of the complexes of quaterthiophene with CNT are investigated. Complexation changed the charge transfer characteristics of quaterthiophene from p-type to n-type.

Assessment of DFT methods for studying acid gas capture by ionic liquids

2015 ◽  
Vol 17 (40) ◽  
pp. 26875-26891 ◽  
Author(s):  
Gregorio García ◽  
Mert Atilhan ◽  
Santiago Aparicio
Keyword(s):  
Ionic Liquids ◽  
Density Functional ◽  
Dft Methods ◽  
Acid Gas ◽  
Density Functional Methods ◽  
Functional Methods ◽  
First Time

For the first time, this work reports an analysis of the performance of Density Functional methods for studying acid gas capture (CO2 and SO2) by ionic liquids (ILs).

The structure and binding energy of K+–ether complexes: A comparison of MP2, RI‐MP2, and density functional methods

1996 ◽  
Vol 105 (5) ◽  
pp. 1940-1950 ◽  
Author(s):  
David Feller ◽  
Edoardo Aprà ◽  
Jeff A. Nichols ◽  
David E. Bernholdt
Keyword(s):  
Binding Energy ◽  
Density Functional ◽  
Density Functional Methods ◽  
Functional Methods

scholarly journals Fast, Accurate Enthalpy Differences in Spin Crossover Crystals from DFT+U

2020 ◽  
Author(s):  
Miriam Ohlrich ◽  
Ben Powell
Keyword(s):  
Density Functional ◽  
Spin Crossover ◽  
Mean Absolute Error ◽  
Computational Cost ◽  
Absolute Error ◽  
Hybrid Functional ◽  
Dft Methods ◽  
Temperature State ◽  
Potential Applications ◽  
Hybrid Functionals

<div>Spin crossover materials are bi-stable systems with potential applications as molecular scale electronic switches, actuators, thermometers, barometers and displays. However, calculating the enthalpy difference, DH, between the high spin (HS) and low spin (LS) states has been plagued with difficulties. For example, many common density functional theory (DFT) methods fail to even predict the correct sign of DH, which determines the low temperature state. Here, we study a collection of Fe(II) and Fe(III) materials, where DH has been measured, and which has previously been used to benchmark density functionals. The best performing hybrid functional, TPSSh, achieves a mean absolute error compared to experiment of 11 kJ/mol for this set of materials. However, hybrid functionals scale badly in the solid state; therefore, local functionals are preferable for studying crystalline materials, where the most interesting SCO phenomena occur. We show that both the Liechtenstein and Dudarev DFT+U methods are a little more accurate than TPSSh. The Dudarev method yields a mean absolute error of 8 kJ/mol for U<sub>eff</sub>=1.6 eV. However, the MAE for both TPSSh and DFT+U are dominated by a single material - if this is excluded from the set then DFT+U achieves chemical accuracy. Thus, DFT+U is an attractive option for calculating the properties of spin crossover crystals, as its accuracy is comparable to that of meta-hybrid functionals, but at a much lower computational cost.</div>

scholarly journals Fast, Accurate Enthalpy Differences in Spin Crossover Crystals from DFT+U

2020 ◽  
Author(s):  
Miriam Ohlrich ◽  
Ben Powell
Keyword(s):  
Density Functional ◽  
Spin Crossover ◽  
Mean Absolute Error ◽  
Computational Cost ◽  
Absolute Error ◽  
Hybrid Functional ◽  
Dft Methods ◽  
Temperature State ◽  
Potential Applications ◽  
Hybrid Functionals

<div>Spin crossover materials are bi-stable systems with potential applications as molecular scale electronic switches, actuators, thermometers, barometers and displays. However, calculating the enthalpy difference, DH, between the high spin (HS) and low spin (LS) states has been plagued with difficulties. For example, many common density functional theory (DFT) methods fail to even predict the correct sign of DH, which determines the low temperature state. Here, we study a collection of Fe(II) and Fe(III) materials, where DH has been measured, and which has previously been used to benchmark density functionals. The best performing hybrid functional, TPSSh, achieves a mean absolute error compared to experiment of 11 kJ/mol for this set of materials. However, hybrid functionals scale badly in the solid state; therefore, local functionals are preferable for studying crystalline materials, where the most interesting SCO phenomena occur. We show that both the Liechtenstein and Dudarev DFT+U methods are a little more accurate than TPSSh. The Dudarev method yields a mean absolute error of 8 kJ/mol for U<sub>eff</sub>=1.6 eV. However, the MAE for both TPSSh and DFT+U are dominated by a single material - if this is excluded from the set then DFT+U achieves chemical accuracy. Thus, DFT+U is an attractive option for calculating the properties of spin crossover crystals, as its accuracy is comparable to that of meta-hybrid functionals, but at a much lower computational cost.</div>

A DFT study of spherands containing five anisyl groups — Highly preorganized to bind the alkali metal

2006 ◽  
Vol 84 (8) ◽  
pp. 1045-1049 ◽  
Author(s):  
Shabaan AK Elroby ◽  
Kyu Hwan Lee ◽  
Seung Joo Cho ◽  
Alan Hinchliffe
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Density Functional ◽  
Ionic Radius ◽  
Binding Energies ◽  
Cavity Size ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Good Agreement

Although anisyl units are basically poor ligands for metal ions, the rigid placements of their oxygens during synthesis rather than during complexation are undoubtedly responsible for the enhanced binding and selectivity of the spherand. We used standard B3LYP/6-31G** (5d) density functional theory (DFT) to investigate the complexation between spherands containing five anisyl groups, with CH2–O–CH2 (2) and CH2–S–CH2 (3) units in an 18-membered macrocyclic ring, and the cationic guests (Li+, Na+, and K+). Our geometric structure results for spherands 1, 2, and 3 are in good agreement with the previously reported X-ray diffraction data. The absolute values of the binding energy of all the spherands are inversely proportional to the ionic radius of the guests. The results, taken as a whole, show that replacement of one anisyl group by CH2–O–CH2 (2) and CH2–S–CH2 (3) makes the cavity bigger and less preorganized. In addition, both the binding and specificity decrease for small ions. The spherands 2 and 3 appear beautifully preorganized to bind all guests, so it is not surprising that their binding energies are close to the parent spherand 1. Interestingly, there is a clear linear relation between the radius of the cavity and the binding energy (R2 = 0.999).Key words: spherands, preorganization, density functional theory, binding energy, cavity size.

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