scholarly journals Localized orbital scaling correction for systematic elimination of delocalization error in density functional approximations

2017 ◽  
Vol 5 (2) ◽  
pp. 203-215 ◽  
Author(s):  
Chen Li ◽  
Xiao Zheng ◽  
Neil Qiang Su ◽  
Weitao Yang
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Polymer Chains ◽  
Band Gaps ◽  
Functional Theory ◽  
Local Scaling ◽  
Self Consistent ◽  
Consistent Manner ◽  
Localized Orbital ◽  
Global And Local

Abstract The delocalization error of popular density functional approximations (DFAs) leads to diversified problems in present-day density functional theory calculations. For achieving a universal elimination of delocalization error, we develop a localized orbital scaling correction (LOSC) framework, which unifies our previously proposed global and local scaling approaches. The LOSC framework accurately characterizes the distributions of global and local fractional electrons, and is thus capable of correcting system energy, energy derivative and electron density in a self-consistent and size-consistent manner. The LOSC–DFAs lead to systematically improved results, including the dissociation of cationic species, the band gaps of molecules and polymer chains, the energy and density changes upon electron addition and removal, and photoemission spectra.

scholarly journals Reactivity of β-Substituted Phosphoenol Pyruvates towards Alkoxides: A Theoretical and Experimental Study

2018 ◽  
Vol 43 (3-4) ◽  
pp. 211-218
Author(s):  
Djilali Bassou ◽  
Amina Ghomri ◽  
Abdelkrim Atmani
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Atomic Charges ◽  
Reaction Products ◽  
Functional Theory ◽  
Reactivity Indices ◽  
Population Analyses ◽  
Major Reaction ◽  
Practical Synthesis ◽  
Global And Local

A new, practical, synthesis of pyruvic orthoesters relying on the conversion of β-substituted phosphoenol pyruvates by the action of alkoxides is described. Our study of the reaction mechanism was done experimentally and also theoretically. Density functional theory calculations were used to explain the major reaction products found experimentally. Geometry optimisations and atomic charges obtained using different population analyses and the global and local reactivity indices, namely global electrophilicity and the Parr function, were obtained at the B3LYP/6-311G(d) level of theory. The experimental reactivity was correctly reproduced using the Parr function.

Contrasting 1D tunnel-structured and 2D layered polymorphs of V2O5: relating crystal structure and bonding to band gaps and electronic structure

2016 ◽  
Vol 18 (23) ◽  
pp. 15798-15806 ◽  
Author(s):  
Thomas M. Tolhurst ◽  
Brett Leedahl ◽  
Justin L. Andrews ◽  
Peter M. Marley ◽  
Sarbajit Banerjee ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Band Gaps ◽  
Structure Property ◽  
Functional Theory ◽  
X Ray ◽  
Structure Property Relationships ◽  
Structure And Bonding

An elucidation of structure–property relationships in V2O5 polymorphs using synchrotron X-ray spectroscopy and density functional theory calculations.

scholarly journals A band-gap database for semiconducting inorganic materials calculated with hybrid functional

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Sangtae Kim ◽  
Miso Lee ◽  
Changho Hong ◽  
Youngchae Yoon ◽  
Hyungmin An ◽  
...  
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Magnetic Ordering ◽  
Density Functional Theory Calculations ◽  
Inorganic Materials ◽  
Band Gaps ◽  
Device Performance ◽  
Photovoltaic Devices ◽  
Hybrid Functional ◽  
Functional Theory

Abstract Semiconducting inorganic materials with band gaps ranging between 0 and 5 eV constitute major components in electronic, optoelectronic and photovoltaic devices. Since the band gap is a primary material property that affects the device performance, large band-gap databases are useful in selecting optimal materials in each application. While there exist several band-gap databases that are theoretically compiled by density-functional-theory calculations, they suffer from computational limitations such as band-gap underestimation and metastable magnetism. In this data descriptor, we present a computational database of band gaps for 10,481 materials compiled by applying a hybrid functional and considering the stable magnetic ordering. For benchmark materials, the root-mean-square error in reference to experimental data is 0.36 eV, significantly smaller than 0.75–1.05 eV in the existing databases. Furthermore, we identify many small-gap materials that are misclassified as metals in other databases. By providing accurate band gaps, the present database will be useful in screening materials in diverse applications.

scholarly journals Structural and electronic properties of oligo- and polythiophenes modified by substituents

2012 ◽  
Vol 3 ◽  
pp. 909-919 ◽  
Author(s):  
Simon P Rittmeyer ◽  
Axel Groß
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Electronic Devices ◽  
Density Functional Theory Calculations ◽  
Building Blocks ◽  
Band Gaps ◽  
Molecular Electronic ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Electronic And Structural Properties

The electronic and structural properties of oligo- and polythiophenes that can be used as building blocks for molecular electronic devices have been studied by using periodic density functional theory calculations. We have in particular focused on the effect of substituents on the electronic structure of thiophenes. Whereas singly bonded substituents, such as methyl, amino or nitro groups, change the electronic properties of thiophene monomers and dimers, they hardly influence the band gap of polythiophene. In contrast, phenyl-substituted polythiophenes as well as vinyl-bridged polythiophene derivatives exhibit drastically modified band gaps. These effects cannot be explained by simple electron removal or addition, as calculations for charged polythiophenes demonstrate.

Electronic Properties of Cr and Mn Doped BN Nanowires

2018 ◽  
Vol 916 ◽  
pp. 69-73
Author(s):  
Sena Güler Özkapı ◽  
Barış Özkapı ◽  
Seyfettin Dalgıç
Keyword(s):  
Density Functional Theory ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Band Gaps ◽  
Functional Theory ◽  
Zinc Blende ◽  
Spin Polarized ◽  
Potential Applications ◽  
Mn Doped

In this work, we have investigated electronic structures of pure and doped (with Cr and Mn atoms, separately) BN nanowires along [001] direction with zinc blende phase by means of density functional theory calculations. Our results show that the substitution doping of nanowires by Cr and Mn atoms decrases the band gaps of the all BN nanowires. Also, spin polarized calculations exhibit that the density of states (DOS) for spin up and spin down electrons are antisymmetric structure for both Cr and Mn doped BN nanowires. All these show that doped BN nanowire systems have potential applications in electronics and spintronics.

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