scholarly journals Feasibility of Predicting Static Dielectric Constants of Polymer Materials: A Density Functional Theory Method

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 284
Author(s):  
Zheng Tang ◽  
Chaofan Chang ◽  
Feng Bao ◽  
Lei Tian ◽  
Huichao Liu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Rapid Development ◽  
Dielectric Constants ◽  
Polymer Materials ◽  
Basis Set ◽  
Basis Sets ◽  
Functional Theory ◽  
Low Dielectric ◽  
Static Dielectric Constants

The rapid development of electronic devices with high integration levels, a light weight, and a multifunctional performance has fostered the design of novel polymer materials with low dielectric constants, which is crucial for the electronic packaging and encapsulation of these electronic components. Theoretical studies are more efficient and cost-effective for screening potential polymer materials with low dielectric constants than experimental investigations. In this study, we used a molecular density functional theory (DFT) approach combined with the B3LYP functional at the 6-31+G(d, p) basis set to validate the feasibility of predicting static dielectric constants of the polymer materials. First, we assessed the influence of the basis sets on the polarizability. Furthermore, the changes of polarizability, polarizability per monomer unit, and differences in polarizability between the consecutive polymer chains as a function of the number of monomers were summarized and discussed. We outlined a similar behavior for the volume of the polymers as well. Finally, we simulated dielectric constants of three typical polymer materials, polyethylene (PE), polytetrafluoroethylene (PTFE), and polystyrene (PS), by combining with the Clausius–Mossotti equation. The simulated results showed excellent agreement with experimental data from the literature, suggesting that this theoretical DFT method has great potential for the molecular design and development of novel polymer materials with low dielectric constants.

Benchmark of Simplified Time-Dependent Density Functional Theory for UV-Vis Spectral Properties of Porphyrinoids

2019 ◽  
Author(s):  
Kamal Batra ◽  
Stefan Zahn ◽  
Thomas Heine
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Absolute Error ◽  
Time Dependent ◽  
Basis Set ◽  
Basis Sets ◽  
Functional Theory ◽  
Framework Materials ◽  
Dependent Density

<p>We thoroughly benchmark time-dependent density- functional theory for the predictive calculation of UV/Vis spectra of porphyrin derivatives. With the aim to provide an approach that is computationally feasible for large-scale applications such as biological systems or molecular framework materials, albeit performing with high accuracy for the Q-bands, we compare the results given by various computational protocols, including basis sets, density-functionals (including gradient corrected local functionals, hybrids, double hybrids and range-separated functionals), and various variants of time-dependent density-functional theory, including the simplified Tamm-Dancoff approximation. An excellent choice for these calculations is the range-separated functional CAM-B3LYP in combination with the simplified Tamm-Dancoff approximation and a basis set of double-ζ quality def2-SVP (mean absolute error [MAE] of ~0.05 eV). This is not surpassed by more expensive approaches, not even by double hybrid functionals, and solely systematic excitation energy scaling slightly improves the results (MAE ~0.04 eV). </p>

scholarly journals Investigation of the Effects of Solvents on the Structural, Electronic and Thermodynamic Properties of Rosiglitazone Based on Density Functional Theory

2019 ◽  
pp. 1-18
Author(s):  
R. A. Ismail ◽  
A. B. Suleiman ◽  
A. S. Gidado ◽  
A. Lawan ◽  
A. Musa
Keyword(s):  
Density Functional Theory ◽  
Dipole Moment ◽  
Thermodynamic Properties ◽  
Gas Phase ◽  
Density Functional ◽  
Dielectric Constants ◽  
Basis Sets ◽  
Lumo Energy ◽  
Functional Theory ◽  
Homo Lumo

Rosiglitazone ( C18H19N3O3S ) is an anti-diabetic drug that reduces insulin resistance in patients with type 2 diabetes. The parameters (bond lengths and bond angles), HOMO, LUMO, HOMO-LUMO energy gap, dipole moment, thermodynamic properties, total energy and vibrational frequencies and intensities of the Rosiglitazone molecule in gas phase and in solvents (Water, Ethanol, DMSO and Acetonitrile) were calculated based on Density Functional Theory (DFT) using standard basis sets: B3LYP/6-31G(d,p), B3LYP/6-31+G(d,p) and B3LYP/6-31++G(d,p). Windows version of Gaussian 09 was used for all the calculations. From the results obtained, the solvents have little influence on the optimized parameters of the molecule. The highest HOMO value of -5.433 eV was found in gas phase showing that the molecule will best donate electron in the gas phase, followed by ethanol in comparison with other solvents. The values of the HOMO were observed to increase with the decrease in dielectric constants of the solvents across all the basis sets used. The lowest LUMO energy of -1.448 eV was found to be in ethanol which shows that the molecule will best accept electron in ethanol compared to the gas phase and other solvents. The largest HOMO-LUMO gap of 4.285 eV was found in water which shows its higher kinetic stability and less chemical reactivity compared to other solvents and in the gas phase. The chemical softness of the molecule was found to decrease as the dielectric constants of the solvents increased namely from ethanol to water. The chemical hardness was found to slightly increase with the increase in dielectric constants of the solvents. The highest value of the dipole moment of 4.6874 D was found in water indicating that the molecule will have the strongest intermolecular interactions in water compared to other solvents and in the gas phase. The total energy increased as the dielectric constants of the solvents decreased from water to ethanol. The vibrational frequencies and intensities increased as the dielectric constants of the solvents increased from ethanol to water. The results confirmed the effects of solvents on the structural, electronic and thermodynamic properties of the studied molecule and will be useful in the design and development of rosiglitazone as an anti-diabetic drug.

Benchmark of Simplified Time-Dependent Density Functional Theory for UV-Vis Spectral Properties of Porphyrinoids

2019 ◽  
Author(s):  
Kamal Batra ◽  
Stefan Zahn ◽  
Thomas Heine
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Absolute Error ◽  
Time Dependent ◽  
Basis Set ◽  
Basis Sets ◽  
Functional Theory ◽  
Framework Materials ◽  
Dependent Density

<p>We thoroughly benchmark time-dependent density- functional theory for the predictive calculation of UV/Vis spectra of porphyrin derivatives. With the aim to provide an approach that is computationally feasible for large-scale applications such as biological systems or molecular framework materials, albeit performing with high accuracy for the Q-bands, we compare the results given by various computational protocols, including basis sets, density-functionals (including gradient corrected local functionals, hybrids, double hybrids and range-separated functionals), and various variants of time-dependent density-functional theory, including the simplified Tamm-Dancoff approximation. An excellent choice for these calculations is the range-separated functional CAM-B3LYP in combination with the simplified Tamm-Dancoff approximation and a basis set of double-ζ quality def2-SVP (mean absolute error [MAE] of ~0.05 eV). This is not surpassed by more expensive approaches, not even by double hybrid functionals, and solely systematic excitation energy scaling slightly improves the results (MAE ~0.04 eV). </p>

A density functional theory study of the free radicals NH2, NF2, NCl2, PH2, PF2, and PCl2

1994 ◽  
Vol 72 (3) ◽  
pp. 695-704 ◽  
Author(s):  
Maggie A. Austen ◽  
Leif A. Eriksson ◽  
Russell J. Boyd
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Basis Set ◽  
Basis Sets ◽  
Functional Theory ◽  
Unpaired Spin ◽  
Non Local ◽  
Local Potentials ◽  
Spin Densities

The linear combination of Gaussian-type orbitals–density functional theory (LCGTO–DFT) approach is used to study geometries and hyperfine structures of a set of neutral radicals. Each of the title molecules is investigated by means of local density approximation calculations, and using the Becke–Perdew and Perdew–Wang–Perdew corrections to the exchange and correlation functionals. The effects of local vs. non-local potentials and of various basis sets are investigated. Total densities and unpaired spin densities are compared. The isotropic couplings are found to be very dependent on the type of exchange functional used, whereas the anisotropic couplings are relatively insensitive to the choice of basis set and functional. In most cases, the Perdew–Wang exchange corrections provide isotropic couplings in satisfactory agreement with experiment.

scholarly journals Vibrational spectra of aniline in gas phase: An ab-initio study

2010 ◽  
Vol 7 (2) ◽  
pp. 449-455
Author(s):  
S. D. S. Chauhan ◽  
A.K. Sharma ◽  
R. Kumar ◽  
D. Kulshreshtha ◽  
R. Gupta ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Basis Set ◽  
Basis Sets ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Hartree Fock ◽  
Modes Of Vibration ◽  
Experimental Findings

Vibrational frequencies of aniline in gas phase have been calculated and each of their modes of vibration assigned properly at RHF and DFT with 6-31G(d) basis set. In the present study, it has been observed that the 6-31G(d) basis set at both RHF and DFT levels of calculations provides better agreement to the experimental findings as compared to other basis sets. Simultaneously, Density functional theory is found to be superior to its counterpart Hartree Fock method.

scholarly journals Basis Set Extrapolations for Density Functional Theory

2020 ◽  
Author(s):  
Peter Kraus
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Computational Cost ◽  
Basis Set ◽  
Basis Sets ◽  
Density Functionals ◽  
Functional Theory ◽  
Common Basis ◽  
Basis Set Extrapolation

Improving results of correlated wavefunction theory calculations by extrapolating from successive basis sets is nowadays a common practice. However, such approaches are uncommon in density functional theory, especially due its faster convergence towards the basis set limit. In this work I present approaches for basis set extrapolation in density functional theory that enable users to obtain results of 4-zeta quality from 3- and 2-zeta calculations, i.e. at a fraction of the computational cost. The extrapolation techniques work well with modern density functionals and common basis sets.<br>

Basis Set Effects in Density Functional Theory Calculation of Muoniated Cytosine Nucleobase

2020 ◽  
Vol 860 ◽  
pp. 282-287
Author(s):  
Wan Nurfadhilah Zaharim ◽  
Shukri Sulaiman ◽  
Saidah Sakinah Mohd Tajudin ◽  
Siti Nuramira Abu Bakar ◽  
Nur Eliana Ismail ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Total Energy ◽  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Geometry Optimization ◽  
Density Functional Theory Method ◽  
Basis Set ◽  
Basis Sets ◽  
Functional Theory ◽  
Muonium Hyperfine

The Density Functional Theory method was employed to investigate the electronic structure and muonium hyperfine interaction of muonium trapped near carbon atom labelled as '5' in cytosine nucleobase. Eighteen different basis sets in combination with B3LYP functional were examined in geometry optimization calculations on the muoniated radical. There are significant quantitative differences in the calculated total energy. The employment of basis set that does not include polarization function produces an optimized structure with high total energy. The 6-311++G(d,p) basis set yielded the lowest total energy as compared to other basis sets. The bond order of muonium trapped at C5 atom is in the range of 0.841 to 0.862. The 6-31G basis set produced the muonium Fermi contact coupling constant that is the closest to the experimental value.

scholarly journals Basis Set Extrapolations for Density Functional Theory

2020 ◽  
Author(s):  
Peter Kraus
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Computational Cost ◽  
Basis Set ◽  
Basis Sets ◽  
Density Functionals ◽  
Functional Theory ◽  
Common Basis ◽  
Basis Set Extrapolation

Improving results of correlated wavefunction theory calculations by extrapolating from successive basis sets is nowadays a common practice. However, such approaches are uncommon in density functional theory, especially due its faster convergence towards the basis set limit. In this work I present approaches for basis set extrapolation in density functional theory that enable users to obtain results of 4-zeta quality from 3- and 2-zeta calculations, i.e. at a fraction of the computational cost. The extrapolation techniques work well with modern density functionals and common basis sets.<br>

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