Basis set effects on frontier molecular orbital energies and energy gaps: A comparative study between plane waves and localized basis functions in molecular systems

2004 ◽  
Vol 120 (22) ◽  
pp. 10359-10363 ◽  
Author(s):  
Myrna H. Matus ◽  
Jorge Garza ◽  
Marcelo Galván
Keyword(s):  
Comparative Study ◽  
Molecular Orbital ◽  
Plane Waves ◽  
Basis Functions ◽  
Basis Set ◽  
Frontier Molecular Orbital ◽  
Molecular Systems ◽  
Orbital Energies ◽  
Energy Gaps

scholarly journals Formulation and Implementation of Density Functional Embedding Theory using Products of Basis Functions

2020 ◽  
Author(s):  
Vladimir Rybkin
Keyword(s):  
Condensed Phase ◽  
Density Functional ◽  
Large Scale ◽  
Plane Waves ◽  
Basis Functions ◽  
Basis Set ◽  
Transfer Reactions ◽  
Molecular Systems ◽  
Embedding Theory ◽  
Proton Transfer Reactions

The representation of embedding potential in using products of AO basis functions has been developed in the context of density functional embedding theory (DFET). The formalism allows to treat pseudopotential and all-electron calculations on the same footing and enables simple transfer of the embedding potential in the compact matrix form. In addition, a simple cost-reduction procedure for basis set and potential reduction has been proposed. The theory has been implemented for the condensed-phase and molecular systems using Gaussian and Plane Waves (GPW) and Gaussian and Augmented Plane Waves (GAPW) formalisms and tested for proton transfer reactions in the cluster and the condensed phase. The computational scaling of the embedding potential optimization is similar to this of hybrid DFT with a significantly reduced prefactor and allows for large-scale applications.<div><br></div>

scholarly journals Formulation and Implementation of Density Functional Embedding Theory using Products of Basis Functions

2020 ◽  
Author(s):  
Vladimir Rybkin
Keyword(s):  
Condensed Phase ◽  
Density Functional ◽  
Large Scale ◽  
Plane Waves ◽  
Basis Functions ◽  
Basis Set ◽  
Transfer Reactions ◽  
Molecular Systems ◽  
Embedding Theory ◽  
Proton Transfer Reactions

The representation of embedding potential in using products of AO basis functions has been developed in the context of density functional embedding theory (DFET). The formalism allows to treat pseudopotential and all-electron calculations on the same footing and enables simple transfer of the embedding potential in the compact matrix form. In addition, a simple cost-reduction procedure for basis set and potential reduction has been proposed. The theory has been implemented for the condensed-phase and molecular systems using Gaussian and Plane Waves (GPW) and Gaussian and Augmented Plane Waves (GAPW) formalisms and tested for proton transfer reactions in the cluster and the condensed phase. The computational scaling of the embedding potential optimization is similar to this of hybrid DFT with a significantly reduced prefactor and allows for large-scale applications.<div><br></div>

Spirochromone-chalcone conjugates as antitubercular agents: synthesis, bio evaluation and molecular modeling studies

RSC Advances ◽  
2015 ◽  
Vol 5 (129) ◽  
pp. 106448-106460 ◽  
Author(s):  
M. Mujahid ◽  
P. Yogeeswari ◽  
D. Sriram ◽  
U. M. V. Basavanag ◽  
Erik Díaz-Cervantes ◽  
...  
Keyword(s):  
Molecular Modeling ◽  
Molecular Orbital ◽  
Frontier Molecular Orbital ◽  
Antitubercular Agents ◽  
Orbital Energies ◽  
Modeling Studies ◽  
Molecular Modeling Studies

We report new spiro chromone scaffold derived molecules possessing in vitro anti-tubercular activities. QSAR based molecular modeling studies correlated the bioactivities with the frontier molecular orbital energies.

scholarly journals Crystal Structure, Hirshfeld Surface and Frontier Molecular Orbital Analyses of N-[2-(trifluoromethyl)phenyl]succinamic Acid

2020 ◽  
Vol 32 (12) ◽  
pp. 3179-3185
Author(s):  
P.A. Suchetan ◽  
S. Naveen ◽  
N.K. Lokanath ◽  
P. Krishna Murthy ◽  
M.V. Deepa Urs
Keyword(s):  
Hydrogen Bonds ◽  
Molecular Orbital ◽  
Density Functional ◽  
Hirshfeld Surface ◽  
Basis Set ◽  
Frontier Molecular Orbital ◽  
Reactivity Descriptors ◽  
Succinamic Acid ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

The ortho-CF3 substituent and the N-H bond are in syn-conformation in N-[2-(trifluoromethyl)phenyl]succinamic acid. In amide and acid functionalities, the carbonyl groups are directed in opposite directions to each other and their related-CH2 groups. syn-Conformation is observed for the acid functionality, where the carbonyl C=O and hydroxyl O-H bonds are directed in the same direction. Three planar fragments comprise of the molecule: aromatic ring (A), core portion -Carm-N(H)-C(=O)-C(H2)-C(H2)(B) and -C(H2)-C(=O)-OH(C). The dihedral angle between a pair of fragments being 48.6(4)º (A and B), 81.6 (4)º (B and C) and 70.5 (5)º (A and C). N-H•••O hydrogen bonds bind the molecules forming C(4) chains in the crystal, and the neighbouring anti-parallel chains are bound by O-H•••O hydrogen bonds resulting in a chair shaped ribbon of one-dimensional nature. The Hirshfeld surface study was carried out, including fingerprint plots. Studies have shown that the interactions with O•••H/H•••O (27.4%), H•••H (27.3%) and H•••F/F•••H (20.2%) substantially added to the surface. Theoretically, the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and various global reactivity descriptors were also computed by the density functional theory (DFT/B3LYP) approach with a 6-311G(d, p) basis set in the ground state on the geometrically optimized structure in the gas phase.

scholarly journals Statistical Prediction of Donor-Acceptor Thiophene Copolymer Properties

2019 ◽  
Author(s):  
Michael Cole ◽  
Ilana Kanal ◽  
Geoffrey Hutchison
Keyword(s):  
Molecular Orbital ◽  
Field Effect Transistors ◽  
Degree Of Polymerization ◽  
Statistical Prediction ◽  
Frontier Molecular Orbital ◽  
Light Emitting ◽  
Orbital Interactions ◽  
Orbital Energies ◽  
Donor Acceptor ◽  
Statistical Relationships

This work illustrates some of the shortcomings of the standard donor-acceptor model as a tool for predicting polymer molecular orbital interactions. 8741 DFT calculations were performed for a series of co-oligomers of varying length from a diverse set of 91 thiophene monomers to explore statistical relationships between the frontier molecular orbital energies of oligomers and their degree of polymerization. These relationships were used to develop predictive models that allow for the calculation of polymer frontier molecular orbital energies. Polymer frontier molecular orbital energies have been shown to impact the device performances of many types of optoelectronic devices, including organic field effect transistors, organic photovoltaics and organic light emitting diodes.

scholarly journals Quantum Mechanical Study on the Structure and Vibrational Spectra of Cyclobutanone and 1,2-Cyclobutanedione

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Anoop kumar Pandey ◽  
Apoorva Dwivedi ◽  
Neeraj Misra
Keyword(s):  
Comparative Study ◽  
Normal Mode Analysis ◽  
Basis Set ◽  
Mode Analysis ◽  
Quantum Mechanical ◽  
Energy Gaps ◽  
Mechanical Study ◽  
Quantum Mechanical Study ◽  
Derivatives Of ◽  
Homo Lumo

For 1,2-cyclobutanedione and cyclobutanone, we have carried out a comparative study of different methods like B3LYP, LSDA, and B3PW91 of DFT using 6-31G (d, p) basis set and MP2 method. On comparing these methods we find that B3PW91 method is closer to the experimental one. So by using B3PW91 method, we have made a comparative study of their structures, normal mode analysis, and other properties of the two derivatives of cyclobutane. The molecular HOMO, LUMO composition, their respective energy gaps, and MESP contours/surfaces have also been drawn to explain the activity of 1,2-cyclobutanedione and cyclobutanone.

scholarly journals Statistical Prediction of Donor-Acceptor Thiophene Copolymer Properties

2019 ◽  
Author(s):  
Michael Cole ◽  
Ilana Kanal ◽  
Geoffrey Hutchison
Keyword(s):  
Molecular Orbital ◽  
Field Effect Transistors ◽  
Degree Of Polymerization ◽  
Statistical Prediction ◽  
Frontier Molecular Orbital ◽  
Light Emitting ◽  
Orbital Interactions ◽  
Orbital Energies ◽  
Donor Acceptor ◽  
Statistical Relationships

This work illustrates some of the shortcomings of the standard donor-acceptor model as a tool for predicting polymer molecular orbital interactions. 8741 DFT calculations were performed for a series of co-oligomers of varying length from a diverse set of 91 thiophene monomers to explore statistical relationships between the frontier molecular orbital energies of oligomers and their degree of polymerization. These relationships were used to develop predictive models that allow for the calculation of polymer frontier molecular orbital energies. Polymer frontier molecular orbital energies have been shown to impact the device performances of many types of optoelectronic devices, including organic field effect transistors, organic photovoltaics and organic light emitting diodes.

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