Structures and Electronic Properties of a Si55 Cluster on DFTB Calculations

2015 ◽  
Vol 815 ◽  
pp. 49-53 ◽  
Author(s):  
Li Jun Wu ◽  
Lin Zhang ◽  
Yang Qi
Keyword(s):  
Genetic Algorithms ◽  
Global Optimization ◽  
Dipole Moment ◽  
Density Functional ◽  
Tight Binding ◽  
Average Energy ◽  
Spherical Shape ◽  
Geometrical Structures ◽  
Molecular Dipole ◽  
Homo Lumo

The lowest-energy geometrical structures of a cluster containing 55 atoms were searched by using the Density Functional Tight Binding (DFTB) combined with unbiased global optimization genetic algorithms (GAs) method. Two lowest-energy structures were obtained for the Si55 cluster with the appearance of “Y shape” and “like-spherical shape” configurations. The configuration dependence average energy, highest occupied and lowest unoccupied molecular (HOMO-LUMO) gap, electron transfer and molecular dipole moment were also discussed in details for this cluster.

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.

scholarly journals Pareto Optimization of Oligomer Polarizability and Dipole Moment using a Genetic Algorithm

2021 ◽  
Author(s):  
Danielle Hiener ◽  
Geoffrey Hutchison
Keyword(s):  
Genetic Algorithm ◽  
Dipole Moment ◽  
High Performance ◽  
Density Functional ◽  
Chemical Space ◽  
Dipole Moments ◽  
Tight Binding ◽  
Dielectric Materials ◽  
Underlying Structure ◽  
Large Set

High performance electronic components are highly sought after in order to produce increasingly smaller and cheaper electronic devices. Drawing inspiration from inorganic dielectric materials, in which both polarizability and polarization contribute, organic materials can also maximize both. For a large set of small molecules drawn from PubChem, a Pareto-like front appears between polarizability and dipole moment indicating the presence of an apparent trade-off between these two properties. We tested this balance in π-conjugated materials by searching for novel conjugated hexamers with simultaneously large polarizabilities and dipole moments with potential use for dielectric materials. Using a genetic algorithm (GA) screening technique in conjunction with an approximate density functional tight binding method (GFN2-xTB) for property calculations, we were able to efficiently search chemical space for optimal hexamers. Given the scope of chemical space, using the GA technique saves considerable time and resources by speeding up molecular searches compared to a systematic search. We also explored the underlying structure-function relationships, including sequence and monomer properties, that characterize large polarizability and dipole moment regimes.

Electronic transport properties in the stable phase of a cumulene/B7/cumulene molecular bridge investigated using density functional theory and a tight-binding method

2019 ◽  
Vol 43 (42) ◽  
pp. 16515-16523 ◽  
Author(s):  
Mohammad Qasemnazhand ◽  
Farhad Khoeini ◽  
Sima Shekarforoush
Keyword(s):  
Density Functional Theory ◽  
Electronic Transport ◽  
Density Functional ◽  
Tight Binding ◽  
Stable Phase ◽  
Binding Parameters ◽  
Functional Theory ◽  
Tight Binding Method ◽  
Homo Lumo ◽  
Molecular Bridge

In this study, we first obtain the single-band tight-binding parameters of a B7 cluster in terms of matching the HOMO–LUMO levels obtained from density functional theory (DFT).

Simulation-Based Optical Spectra Analyses and Synthesis of Highly Monodispersed Mn-Doped ZnSe Nanocrystal

NANO ◽  
2016 ◽  
Vol 11 (08) ◽  
pp. 1650086 ◽  
Author(s):  
Mukerem H. Abib ◽  
Xudong Yao ◽  
Guopeng Li ◽  
Longfei Mi ◽  
Yajing Chang ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Molecular Orbital ◽  
Density Functional ◽  
Optical Absorption Spectra ◽  
Geometrical Structures ◽  
Gap Energy ◽  
Lowest Unoccupied Molecular Orbital ◽  
Average Size ◽  
Homo Lumo

Geometrical structures of (ZnSe)n, [Formula: see text], ([Formula: see text] 1–4) and (MnxZn[Formula: see text]Se[Formula: see text], ([Formula: see text] clusters were calculated using density functional theory (DFT). Optical/absorption spectra, Raman spectra, HOMO–LUMO gap energy and binding energy of each cluster were calculated. The calculated results show the red shift of the optical/absorption spectra band caused by the manganese atoms doped in ZnSe clusters, and the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO–LUMO) gap energy value is decreased. Furthermore, we realized highly monodispersed manganese-doped zinc selenide quantum dots (Mn:ZnSe d-dots) experimentally by using a convenient route. The as-synthesized Mn:ZnSe d-dots were characterized by UV-Vis absorption, photoluminescence (PL), X-ray diffraction (XRD), TEM and HRTEM. The experimental results revealed that the as-prepared Mn:ZnSe d-dots with zinc-blende structure have an average size of about 3.9 nm.

scholarly journals Pareto Optimization of Oligomer Polarizability and Dipole Moment using a Genetic Algorithm

2021 ◽  
Author(s):  
Danielle Hiener ◽  
Geoffrey Hutchison
Keyword(s):  
Genetic Algorithm ◽  
Dipole Moment ◽  
High Performance ◽  
Density Functional ◽  
Chemical Space ◽  
Dipole Moments ◽  
Tight Binding ◽  
Dielectric Materials ◽  
Underlying Structure ◽  
Large Set

High performance electronic components are highly sought after in order to produce increasingly smaller and cheaper electronic devices. Drawing inspiration from inorganic dielectric materials, in which both polarizability and polarization contribute, organic materials can also maximize both. For a large set of small molecules drawn from PubChem, a Pareto-like front appears between polarizability and dipole moment indicating the presence of an apparent trade-off between these two properties. We tested this balance in π-conjugated materials by searching for novel conjugated hexamers with simultaneously large polarizabilities and dipole moments with potential use for dielectric materials. Using a genetic algorithm (GA) screening technique in conjunction with an approximate density functional tight binding method (GFN2-xTB) for property calculations, we were able to efficiently search chemical space for optimal hexamers. Given the scope of chemical space, using the GA technique saves considerable time and resources by speeding up molecular searches compared to a systematic search. We also explored the underlying structure-function relationships, including sequence and monomer properties, that characterize large polarizability and dipole moment regimes.

A Theoretical Study of Lithium-Doped Gallium Clusters by Density Functional Theory

2012 ◽  
Vol 67 (5) ◽  
pp. 289-295 ◽  
Author(s):  
Şükrü Şentürk ◽  
Yavuz Ekincioğlu
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Surface Effect ◽  
Geometrical Structures ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Lowest Unoccupied Molecular Orbital ◽  
The Stability ◽  
Average Bond ◽  
Homo Lumo

The geometrical structures, stabilities, and electronic properties of GanLi (n = 1 - 13) clusters were investigated within the density functional theory (DFT). The impurity lithium atom enhances the stability of GanLi (n = 1 - 13) clusters, especially GanLi (n = 9 - 13) compared to Gan(n = 9 - 14), that is at either apex position or side position. The dissociation energy, second-order energy differences, and the energy gaps between highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) indicate that the Ga7Li, Ga9Li, and Ga11Li clusters are more stable within the studied cluster range. Moreover, the variation of the average bond length of Ga-Li is due to the surface effect, and the binding strength increases resulting from the increase of charge amount.

Three 1-phenylindolin-2-one derivatives displaying different molecular dipole moments and different crystallographic symmetries

2015 ◽  
Vol 71 (1) ◽  
pp. 69-74 ◽  
Author(s):  
Lei Wang ◽  
Man Zhang ◽  
Ying-Ying Jin ◽  
Qing Lu ◽  
Qi Fang
Keyword(s):  
Density Functional Theory ◽  
Dipole Moment ◽  
Dft Calculations ◽  
Density Functional ◽  
Dipole Moments ◽  
Polar Space ◽  
Functional Theory ◽  
Polar Structure ◽  
Molecular Dipole ◽  
Space Groups

Three 1-phenylindolin-2-one derivatives, namely 1-phenylindolin-2-one, C14H11NO, (I), 5-bromo-1-phenylindolin-2-one, C14H10BrNO, (II), and 5-iodo-1-phenylindolin-2-one, C14H10INO, (III), have been synthesized and their structures determined. Compounds (I) and (II) crystallized in the centrosymmetric space groupsPbcaandP21/c, respectively, while compound (III) crystallized in the polar space groupAea2. Density functional theory (DFT) calculations show that the molecular dipole moment gradually decreases in the order (I) > (II) > (III). The relatively smaller dipole moment of (III) and the larger non-electrostatic intermolecular interactions may be the main reasons for the noncentrosymmetric and polar structure of (III).

scholarly journals DFT analysis of Thymine adsorption on Ti doped graphene for biosensor applications

2021 ◽  
Vol 2070 (1) ◽  
pp. 012012
Author(s):  
Jawaher Qasem ◽  
Prashant Pardeshi ◽  
Avinash Ingle ◽  
Ravindra Karde ◽  
Shamsan Ali ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Dipole Moment ◽  
Quantum Chemical ◽  
Density Functional ◽  
Pristine Graphene ◽  
Functional Theory ◽  
Energy Mode ◽  
Doped Graphene ◽  
Homo Lumo ◽  
Biosensor Applications

Abstract Density functional theory quantum chemical calculations have been performed to investigate the adsorption of thymine on pristine graphene (Gr) and Titanium doped graphene (GrTi) in order to explore the potential of doped graphene as adsorbent for biomolecule DNA nucleobase thymine. The various parameters including adsorption energy, mode of charge transfer, dipole moment, HOMO-LUMO gap and DOS confirms the Ti doped graphene can be good candidate as adsorbent for thymine in terms of biosensor applications.

DFT investigation on interaction of chlorine with In2O3 nanostructures

2015 ◽  
Vol 93 (11) ◽  
pp. 1249-1260 ◽  
Author(s):  
V. Nagarajan ◽  
R. Chandiramouli
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Population Analysis ◽  
Average Energy ◽  
Adsorption Properties ◽  
Basis Set ◽  
Mixed Gas ◽  
Mulliken Population ◽  
Adsorption Sites ◽  
Homo Lumo

The structural, electronic, and adsorption properties of chlorine on pristine, tin-, aluminum-, and fluorine-substituted In2O3 nanostructures are successfully optimized and computed using density functional theory along with the B2LYP/LanL2DZ basis set. The electronic properties of pristine, tin-, aluminum-, and fluorine-substituted In2O3 nanostructures are discussed in terms of ionization potential, HOMO–LUMO gap, and electron affinity. The dipole moment and point symmetry group of In2O3 nanostructures are also reported. The structural stability of pristine, tin-, aluminum-, and fluorine-substituted In2O3 nanostructures are investigated in terms of formation energy. The adsorption properties of chlorine on In2O3 are studied and the most appropriate adsorption sites of Cl2 on In2O3 nanostructures are reported. The adsorption properties of hydrogen on In2O3 nanostructures are also investigated and inferred that In2O3 exhibits good sensing characteristics towards hydrogen. The adsorbed energy, HOMO–LUMO gap, Mulliken population analysis, and average energy gap variation are used to identify the prominent adsorption site of Cl2 on In2O3 material. The substitution of fluorine in In2O3 nanostructures enhances the Cl2 adsorption properties in the mixed gas atmosphere.

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