scholarly journals Benchmarking DFT Approaches for the Calculation of Polarizability Inputs for Refractive Index Predictions in Organic Polymers

2019 ◽  
Author(s):  
Mohammad Atif Faiz Afzal ◽  
Johannes Hachmann
Keyword(s):  
High Throughput Screening ◽  
Density Functional ◽  
Ad Hoc ◽  
Late Onset ◽  
Index Of Refraction ◽  
Organic Polymers ◽  
Lorenz Equation ◽  
The Density Functional Theory ◽  
Extrapolation Scheme ◽  
Dft Model

<pre>In a previous study, we introduced a new computational protocol to accurately predict the index of refraction (RI) of organic polymers using a combination of <i>first-principles</i> and data modeling. This protocol is based on the Lorentz-Lorenz equation and involves the calculation of static polarizabilities and number densities of oligomer sequences, which are extrapolated to the polymer limit. We chose to compute the polarizabilities within the density functional theory (DFT) framework using the PBE0/def2-TZVP-D3 model chemistry. While this <i>ad hoc</i> choice proved remarkably successful, it is also relatively expensive from a computational perspective. It represents the bottleneck step in the overall RI modeling protocol, thus limiting its utility for virtual high-throughput screening studies, in which efficiency is essential. For polymers that exhibit late-onset extensivity, the employed linear extrapolation scheme can require demanding calculations on long-oligomer sequences, thus becoming another bottleneck.</pre> <pre>In the work presented here, we benchmark DFT model chemistries to identify approaches that optimize the balance between accuracy and efficiency for this application domain. We compare results for conjugated and non-conjugated polymers, augment our original extrapolation approach with a non-linear option, analyze how the polarizability errors propagate into the RI predictions, and offer guidance for method selection. </pre>

scholarly journals Benchmarking DFT Approaches for the Calculation of Polarizability Inputs for Refractive Index Predictions in Organic Polymers

2019 ◽  
Author(s):  
Mohammad Atif Faiz Afzal ◽  
Johannes Hachmann
Keyword(s):  
High Throughput Screening ◽  
Density Functional ◽  
Ad Hoc ◽  
Late Onset ◽  
Index Of Refraction ◽  
Organic Polymers ◽  
Lorenz Equation ◽  
The Density Functional Theory ◽  
Extrapolation Scheme ◽  
Dft Model

<pre>In a previous study, we introduced a new computational protocol to accurately predict the index of refraction (RI) of organic polymers using a combination of <i>first-principles</i> and data modeling. This protocol is based on the Lorentz-Lorenz equation and involves the calculation of static polarizabilities and number densities of oligomer sequences, which are extrapolated to the polymer limit. We chose to compute the polarizabilities within the density functional theory (DFT) framework using the PBE0/def2-TZVP-D3 model chemistry. While this <i>ad hoc</i> choice proved remarkably successful, it is also relatively expensive from a computational perspective. It represents the bottleneck step in the overall RI modeling protocol, thus limiting its utility for virtual high-throughput screening studies, in which efficiency is essential. For polymers that exhibit late-onset extensivity, the employed linear extrapolation scheme can require demanding calculations on long-oligomer sequences, thus becoming another bottleneck.</pre> <pre>In the work presented here, we benchmark DFT model chemistries to identify approaches that optimize the balance between accuracy and efficiency for this application domain. We compare results for conjugated and non-conjugated polymers, augment our original extrapolation approach with a non-linear option, analyze how the polarizability errors propagate into the RI predictions, and offer guidance for method selection. </pre>

scholarly journals Benchmarking DFT Approaches for the Calculation of Polarizability Inputs for Refractive Index Predictions in Organic Polymers

2018 ◽  
Author(s):  
Mohammad Atif Faiz Afzal ◽  
Johannes Hachmann
Keyword(s):  
High Throughput Screening ◽  
Density Functional ◽  
Ad Hoc ◽  
Late Onset ◽  
Index Of Refraction ◽  
Organic Polymers ◽  
Lorenz Equation ◽  
The Density Functional Theory ◽  
Extrapolation Scheme ◽  
Dft Model

<pre>In a previous study, we introduced a new computational protocol to accurately predict the index of refraction (RI) of organic polymers using a combination of <i>first-principles</i> and data modeling. This protocol is based on the Lorentz-Lorenz equation and involves the calculation of static polarizabilities and number densities of oligomer sequences, which are extrapolated to the polymer limit. We chose to compute the polarizabilities within the density functional theory (DFT) framework using the PBE0/def2-TZVP-D3 model chemistry. While this <i>ad hoc</i> choice proved remarkably successful, it is also relatively expensive from a computational perspective. It represents the bottleneck step in the overall RI modeling protocol, thus limiting its utility for virtual high-throughput screening studies, in which efficiency is essential. For polymers that exhibit late-onset extensivity, the employed linear extrapolation scheme can require demanding calculations on long-oligomer sequences, thus becoming another bottleneck.</pre> <pre>In the work presented here, we benchmark DFT model chemistries to identify approaches that optimize the balance between accuracy and efficiency for this application domain. We compare results for conjugated and non-conjugated polymers, augment our original extrapolation approach with a non-linear option, analyze how the polarizability errors propagate into the RI predictions, and offer guidance for method selection. </pre>

Combining First-Principles and Data Modeling for the Accurate Prediction of the Refractive Index of Organic Polymers

2017 ◽  
Author(s):  
Mohammad Atif Faiz Afzal ◽  
Chong Cheng ◽  
Johannes Hachmann
Keyword(s):  
First Principles ◽  
Data Modeling ◽  
Accurate Prediction ◽  
Index Of Refraction ◽  
Structure Theory ◽  
Organic Polymers ◽  
Number Density ◽  
Lorenz Equation ◽  
In Silico Studies ◽  
Wide Range

Organic materials with a high index of refraction (RI) are attracting considerable interest due to their potential application in optic and optoelectronic devices. However, most of these applications require an RI value of 1.7 or larger, while typical carbon-based polymers only exhibit values in the range of 1.3–1.5. This paper introduces an efficient computational protocol for the accurate prediction of RI values in polymers to facilitate in silico studies that an guide the discovery and design of next-generation high-RI materials. Our protocol is based on the Lorentz-Lorenz equation and is parametrized by the polarizability and number density values of a given candidate compound. In the proposed scheme, we compute the former using first-principles electronic structure theory and the latter using an approximation based on van der Waals volumes. The critical parameter in the number density approximation is the packing fraction of the bulk polymer, for which we have devised a machine learning model. We demonstrate the performance of the proposed RI protocol by testing its predictions against the experimentally known RI values of 112 optical polymers. Our approach to combine first-principles and data modeling emerges as both a successful and highly economical path to determining the RI values for a wide range of organic polymers.

Shifting in optoelectronic properties from pure K2O and Rb2O compounds to their V- and Cr-doped alloys

2018 ◽  
Vol 32 (10) ◽  
pp. 1850116
Author(s):  
Mohammed El Amine Monir ◽  
Hayat Ullah ◽  
Hadj Baltach ◽  
Younes Mouchaal ◽  
Omar Merabiha ◽  
...  
Keyword(s):  
Density Functional ◽  
Optoelectronic Properties ◽  
Index Of Refraction ◽  
Complex Dielectric Constant ◽  
Metallic Behavior ◽  
Functional Theory ◽  
Optical Functions ◽  
Energy Part ◽  
The Density Functional Theory ◽  
Constant Complex

First principle calculations within the density functional theory (DFT) have been used in this approach to study the electronic and optical properties of vanadium (V) and chromium (Cr) doped K2O and Rb2O compounds. Based on the structure properties reported in our previous work, the study of electronic and optoelectronic properties of V- and Cr-doped K2O and Rb2O alloys have been vastly investigated. K2O and Rb2O are found to be semiconductors while their V- and Cr-alloys are metallic in nature. The optical functions like complex dielectric constant, complex index of refraction, absorption coefficient, and reflectivity of these alloys are computed and compared with those of pure K2O and Rb2O compounds. It has been shown that due to TM-doping (TM = V and Cr transition metals), many distinguished peaks appeared in the lower energy part (infrared) of the spectrum. The negative value of [Formula: see text] ([Formula: see text]) in this energy range confirmed the metallic behavior of these alloys. Furthermore, the frequency-dependent optical conductivity is also predicted in the entire spectrum, where it increases with increasing photon energy for all the studied alloys. The significant results of [Formula: see text] ([Formula: see text]) predict that all these compounds are useful in different optoelectronic applications in a wide part of the spectrum (between 13 eV and 27 eV).

Benchmarking DFT approaches for the calculation of polarizability inputs for refractive index predictions in organic polymers

2019 ◽  
Vol 21 (8) ◽  
pp. 4452-4460 ◽  
Author(s):  
Mohammad Atif Faiz Afzal ◽  
Johannes Hachmann
Keyword(s):  
Refractive Index ◽  
High Throughput ◽  
High Index ◽  
Index Of Refraction ◽  
Organic Polymers ◽  
Dft Model

We benchmark DFT model chemistries to identify approaches that optimize the balance between accuracy and efficiency for this virtual high-throughput studies of polymers with high index of refraction.

Combining First-Principles and Data Modeling for the Accurate Prediction of the Refractive Index of Organic Polymers

2017 ◽  
Author(s):  
Mohammad Atif Faiz Afzal ◽  
Chong Cheng ◽  
Johannes Hachmann
Keyword(s):  
First Principles ◽  
Data Modeling ◽  
Accurate Prediction ◽  
Index Of Refraction ◽  
Structure Theory ◽  
Organic Polymers ◽  
Number Density ◽  
Lorenz Equation ◽  
In Silico Studies ◽  
Wide Range

Organic materials with a high index of refraction (RI) are attracting considerable interest due to their potential application in optic and optoelectronic devices. However, most of these applications require an RI value of 1.7 or larger, while typical carbon-based polymers only exhibit values in the range of 1.3–1.5. This paper introduces an efficient computational protocol for the accurate prediction of RI values in polymers to facilitate in silico studies that an guide the discovery and design of next-generation high-RI materials. Our protocol is based on the Lorentz-Lorenz equation and is parametrized by the polarizability and number density values of a given candidate compound. In the proposed scheme, we compute the former using first-principles electronic structure theory and the latter using an approximation based on van der Waals volumes. The critical parameter in the number density approximation is the packing fraction of the bulk polymer, for which we have devised a machine learning model. We demonstrate the performance of the proposed RI protocol by testing its predictions against the experimentally known RI values of 112 optical polymers. Our approach to combine first-principles and data modeling emerges as both a successful and highly economical path to determining the RI values for a wide range of organic polymers.

scholarly journals Using DFT to Calculate the Parameters of the Crystal Field in Mn2+ Doped Hydroxyapatite Crystals

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1050
Author(s):  
Daria Vladimirovna Shurtakova ◽  
Peter Olegovich Grishin ◽  
Marat Revgerovich Gafurov ◽  
Georgy Vladimirovich Mamin
Keyword(s):  
Crystal Field ◽  
Density Functional ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Microwave Frequencies ◽  
The Density Functional Theory ◽  
Dft Model ◽  
Crystal Field Parameters ◽  
Electron Paramagnetic ◽  
Hydroxyapatite Crystals

Crystal field parameters for two nonequivalent positions Ca (I) and Ca (II) for hydroxyapatite (HAp) crystals from the density functional theory (DFT) are calculated. Calculations are compared with the experimental electron paramagnetic resonance (EPR) spectra (registered at two microwave frequencies) for the synthesized Mn-HAp powders Ca9.995Mn0.005(PO4)6(OH)2. It is found that in the investigated species, the manganese is redistributed between both calcium sites with prevalence in Ca (I). Agreement between the calculated and experimental data proves that crystal field parameters in HAp can be calculated in the classical DFT model using the distributed electron density.

scholarly journals Strain Investigation on Spin-Dependent Transport Properties of γ-Graphyne Nanoribbon Between Gold Electrodes

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yun Li ◽  
Xiaobo Li ◽  
Shidong Zhang ◽  
Liemao Cao ◽  
Fangping Ouyang ◽  
...  
Keyword(s):  
Transport Properties ◽  
High Performance ◽  
Density Functional ◽  
Strain Engineering ◽  
Molecular Junctions ◽  
Spin Splitting ◽  
Functional Theory ◽  
Spin Dependent Transport ◽  
The Density Functional Theory ◽  
Dependent Transport

AbstractStrain engineering has become one of the effective methods to tune the electronic structures of materials, which can be introduced into the molecular junction to induce some unique physical effects. The various γ-graphyne nanoribbons (γ-GYNRs) embedded between gold (Au) electrodes with strain controlling have been designed, involving the calculation of the spin-dependent transport properties by employing the density functional theory. Our calculated results exhibit that the presence of strain has a great effect on transport properties of molecular junctions, which can obviously enhance the coupling between the γ-GYNR and Au electrodes. We find that the current flowing through the strained nanojunction is larger than that of the unstrained one. What is more, the length and strained shape of the γ-GYNR serves as the important factors which affect the transport properties of molecular junctions. Simultaneously, the phenomenon of spin-splitting occurs after introducing strain into nanojunction, implying that strain engineering may be a new means to regulate the electron spin. Our work can provide theoretical basis for designing of high performance graphyne-based devices in the future.

scholarly journals Electron-phonon interaction in In-induced √7 ×√3 structures on Si(111) from first-principles

2021 ◽  
Author(s):  
I. Yu. Sklyadneva ◽  
Rolf Heid ◽  
Pedro Miguel Echenique ◽  
Evgueni Chulkov
Keyword(s):  
Density Functional Theory ◽  
Double Layer ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Single Layer ◽  
Phonon Interaction ◽  
Functional Theory ◽  
Electron Phonon Interaction ◽  
The Density Functional Theory

Electron-phonon interaction in the Si(111)-supported rectangular √(7 ) ×√3 phases of In is investigated within the density-functional theory and linear-response. For both single-layer and double-layer √(7 ) ×√3 structures, it...

Sign in / Sign up

Export Citation Format

Share Document