scholarly journals A Density Functional Theory Investigation of Intramolecular Dispersion Forces in Buckyball-Buckybowl Complexes

2021 ◽  
Author(s):  
◽  
Ivan Welsh

<p>The electron-rich, concave face of corannulene makes it an ideal candidate to host electron-deficient fullerenes, such as C60. The host–guest system is dominated by weak van derWaals interactions. Modelling of the C60@corannulene complex was carried out with nine different density functionals: B3LYP, B97-D, BP86, CAM-B3LYP, M06-2X, PW91, t-HCTH, wB97X, and wB97X-D, using the 6-31G(d) basis set. Results indicated that the functionals including an empirical dispersion correction term, B97-D and wB97X-D, gave the most reliable binding energy values when compared with ab initio SCS-MP2 benchmark computations. Additionally, a number of complexes with functionalised corannulene bowls were modelled at the wB97X-D/6-31G(d) level, with NMR calculations performed at the GIAO/wB97X-D/dec-6-31G(d) level. A linear trend was revealed between the number of substituents on corannulene and the strength of binding within complex with C60. Calculated 1H NMR Dd values for methyl groups on methyl substituted corannulene bowls were also linearly dependent on binding energy. Further results are reported here.</p>

2021 ◽  
Author(s):  
◽  
Ivan Welsh

<p>The electron-rich, concave face of corannulene makes it an ideal candidate to host electron-deficient fullerenes, such as C60. The host–guest system is dominated by weak van derWaals interactions. Modelling of the C60@corannulene complex was carried out with nine different density functionals: B3LYP, B97-D, BP86, CAM-B3LYP, M06-2X, PW91, t-HCTH, wB97X, and wB97X-D, using the 6-31G(d) basis set. Results indicated that the functionals including an empirical dispersion correction term, B97-D and wB97X-D, gave the most reliable binding energy values when compared with ab initio SCS-MP2 benchmark computations. Additionally, a number of complexes with functionalised corannulene bowls were modelled at the wB97X-D/6-31G(d) level, with NMR calculations performed at the GIAO/wB97X-D/dec-6-31G(d) level. A linear trend was revealed between the number of substituents on corannulene and the strength of binding within complex with C60. Calculated 1H NMR Dd values for methyl groups on methyl substituted corannulene bowls were also linearly dependent on binding energy. Further results are reported here.</p>


2019 ◽  
Vol 10 (1) ◽  
pp. 144
Author(s):  
Amit Kumar ◽  
Roberto Baccoli ◽  
Antonella Fais ◽  
Alberto Cincotti ◽  
Luca Pilia ◽  
...  

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.


2020 ◽  
Vol 224 ◽  
pp. 145-165
Author(s):  
Derk Pieter Kooi ◽  
Paola Gori-Giorgi

We analyse a path to construct density functionals for the dispersion interaction energy from an expression in terms of the ground state densities and exchange–correlation holes of the isolated fragments.


2018 ◽  
Author(s):  
Diptarka Hait ◽  
Martin Head-Gordon

Static polarizabilities are the first response of the electron density to electric fields, and are therefore important for predicting intermolecular and molecule-field interactions. They also offer a global measure of the accuracy of the treatment of excited states by density functionals in a formally exact manner. We have developed a database of benchmark static polarizabilities for 132 small species at equilibrium geometry, using coupled cluster theory through triple excitations (extrapolated to the complete basis set limit), for the purpose of developing and assessing density functionals. The performance of 60 popular and recent functionals are also assessed, which indicates that double hybrid functionals perform the best, having RMS errors in the range of 2.5-3.8% . Many hybrid functionals also give quite reasonable estimates with 4-5% RMSE. A few meta-GGAs like mBEEF and MVS yield performance comparable to hybrids, indicating potential for improved excited state predictions relative to typical local functionals. Some recent functionals however are found to be prone to catastrophic failure (possibly as a consequence of overparameterization), indicating a need for caution in applying these.


2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Norma Flores-Holguín ◽  
Juan Frau ◽  
Daniel Glossman-Mitnik

Five density functionals, CAM-B3LYP, LC-ωHPBE, MN12SX, N12SX, and ωB97XD, in connection with the Def2TZVP basis set were assessed together with the SMD solvation model for the calculation of the molecular properties, chemical reactivities, and solubilities of some pigments derived from astaxanthin, β-cryptoxanthin, fucoxanthin, myxol, siphonaxanthin, siphonein, and zeaxanthin marine carotenoids in the presence of different solvents (hexane, methanol, ethanol, and water). All the chemical reactivity descriptors for the systems were calculated via conceptual density functional theory (CDFT). Finally, the potential bioavailability and druggability as well as the bioactivity scores for the marine carotenoid pigments were predicted through different methodologies already reported in the literature, which have been previously validated during the study of other natural products obtained from marine sources.


2011 ◽  
Vol 110-116 ◽  
pp. 315-320
Author(s):  
M. R. Sonawane ◽  
B. J. Nagare

We report reactivity of silicon doped single walled carbon nanotube (Si-CNT) towards the small atmospheric gas molecules O2, CO2, SO2and NO2using density functional theory based on the numerical basis set method. The reactivity of these molecules is explained on the basis of electronic properties such as binding energy, charge density, charge transfer and density of states. The large change in binding energy and formation of sigma (σ) bonds between silicon and oxygen atoms shows the strong chemisorption of the molecules on Si-CNT. Further, the density of states analysis clearly illustrate the reduction in the band gap and creation of extra state near the Fermi level, which acts as a catalytic center for adsorption of the molecules. The Mulliken population analysis indicates the charge transfer from Si-CNT to the molecules due to their more electronegativity.


2020 ◽  
Author(s):  
Peter Kraus

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>


2020 ◽  
Author(s):  
Peter Kraus

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>


2018 ◽  
Author(s):  
Diptarka Hait ◽  
Martin Head-Gordon

Static polarizabilities are the first response of the electron density to electric fields, and are therefore important for predicting intermolecular and molecule-field interactions. They also offer a global measure of the accuracy of the treatment of excited states by density functionals in a formally exact manner. We have developed a database of benchmark static polarizabilities for 132 small species at equilibrium geometry, using coupled cluster theory through triple excitations (extrapolated to the complete basis set limit), for the purpose of developing and assessing density functionals. The performance of 60 popular and recent functionals are also assessed, which indicates that double hybrid functionals perform the best, having RMS errors in the range of 2.5-3.8% . Many hybrid functionals also give quite reasonable estimates with 4-5% RMSE. A few meta-GGAs like mBEEF and MVS yield performance comparable to hybrids, indicating potential for improved excited state predictions relative to typical local functionals. Some recent functionals however are found to be prone to catastrophic failure (possibly as a consequence of overparameterization), indicating a need for caution in applying these.


Sign in / Sign up

Export Citation Format

Share Document