Screened hybrid meta-GGA exchange–correlation functionals for extended systems

2019 ◽  
Vol 21 (6) ◽  
pp. 3002-3015 ◽  
Author(s):  
Subrata Jana ◽  
Prasanjit Samal
Keyword(s):  
Solid State ◽  
Exchange Correlation ◽  
Hartree Fock ◽  
Extended Systems

Screened Hartree–Fock exchange integrated with semilocal exchange–correlation functionals often proficiently predict several solid-state properties.

scholarly journals Optical Properties of Silver-Mediated DNA from Molecular Dynamics and Time Dependent Density Functional Theory

2018 ◽  
Vol 19 (8) ◽  
pp. 2346 ◽  
Author(s):  
Esko Makkonen ◽  
Patrick Rinke ◽  
Olga Lopez-Acevedo ◽  
Xi Chen
Keyword(s):  
Molecular Dynamics ◽  
Density Functional ◽  
Time Dependent ◽  
Basis Set ◽  
Dna Nanostructures ◽  
Exchange Correlation ◽  
Hartree Fock ◽  
Spurious Peak ◽  
20 Nm ◽  
Dependent Density

We report a combined quantum mechanics/molecular mechanics (QM/MM) molecular dynamics and time-dependent density functional (TDDFT) study of metal-mediated deoxyribonucleic acid (M-DNA) nanostructures. For the Ag + -mediated guanine tetramer, we found the maug-cc-pvdz basis set to be sufficient for calculating electronic circular dichroism (ECD) spectra. Our calculations further show that the B3LYP, CAM-B3LYP, B3LYP*, and PBE exchange-correlation functionals are all able to predict negative peaks in the measured ECD spectra within a 20 nm range. However, a spurious positive peak is present in the CAM-B3LYP ECD spectra. We trace the origins of this spurious peak and find that is likely due to the sensitivity of silver atoms to the amount of Hartree–Fock exchange in the exchange-correlation functional. Our presented approach provides guidance for future computational investigations of other Ag + -mediated DNA species.

scholarly journals Solid-State Testing of a Van-Der-Waals-Corrected Exchange-Correlation Functional Based on the Semiclassical Atom Theory

Computation ◽  
2018 ◽  
Vol 6 (1) ◽  
pp. 7 ◽  
Author(s):  
Aleksandr Terentjev ◽  
Pietro Cortona ◽  
Lucian Constantin ◽  
José Pitarke ◽  
Fabio Della Sala ◽  
...  
Keyword(s):  
Solid State ◽  
Van Der Waals ◽  
State Testing ◽  
Exchange Correlation ◽  
Atom Theory

Ab initio Correlation Effects in Density Functional Theories: An Electron-Distribution-Based Study for Neon

2005 ◽  
Vol 70 (8) ◽  
pp. 1157-1176 ◽  
Author(s):  
Karol Jankowski ◽  
Ireneusz Grabowski ◽  
Krzysztof Nowakowski ◽  
Jan Wasilewski
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Physical Nature ◽  
Correlation Effects ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Hartree Fock ◽  
Brueckner Orbitals ◽  
Local Gradient ◽  
The Impact

We have briefly reviewed the idea of studies aiming at such a bridging of the methodological gap between ab initio methods (or wave function theory (WFT)) and density functional theory (DFT) that would afford carrying over results concerning details of the structure of correlation effects from one method to the other. Special attention is paid to the problem of coverage of the WFT correlation effects by the exchange-correlation functionals of DFT. A short survey of the concept of supplementing energy-based investigations in this field by electron-density-based studies is given and illustrated by results for the Ne atom. DFT densities are generated for representatives of all four generations of presently used exchange-correlation functionals, including the recently developed orbital-dependent one. These densities are compared with WFT densities calculated at the MP2, MP3, and Brueckner determinant levels. It is found that the exchange-only parts of the local, gradient-corrected, and hybrid functionals account for the bulk of WFT correlation effects. The impact of the associated correlation functionals is very small and their physical nature is not quite clear. The situation is different for the orbital-dependent functional for which the exchange-only functional provides an almost exact description of the Hartree-Fock density. Here, the correlation effects are entirely represented by the correlation functional. Attention is also paid to the suitability of Kohn-Sham orbitals for the description of WFT correlation effects and to their presumptive similarity with Brueckner orbitals.

scholarly journals Accurate Hartree-Fock energy of extended systems using large Gaussian basis sets

2009 ◽  
Vol 80 (17) ◽  
Author(s):  
Joachim Paier ◽  
Cristian V. Diaconu ◽  
Gustavo E. Scuseria ◽  
Manuel Guidon ◽  
Joost VandeVondele ◽  
...  
Keyword(s):  
Basis Sets ◽  
Gaussian Basis Sets ◽  
Hartree Fock ◽  
Extended Systems

Particle-hole pair and beelectron states in ZnO/(Zn,Mg)O quantum wells and Dirac materials.

2015 ◽  
Vol 10 (1) ◽  
pp. 2583-2604
Author(s):  
Lyubov E. Lokot
Keyword(s):  
Quantum Well ◽  
Charge Density ◽  
Heavy Hole ◽  
Wave Functions ◽  
One Dimensional ◽  
Exchange Correlation ◽  
Hartree Fock ◽  
Exchange Correlation Potential ◽  
Correlation Potential ◽  
The One

In this paper a theoretical studies of the space separation of electron and hole wave functions in the quantum well ZnO/Mg(0.27)Zn(0.73)O are presented. For this aim the self-consistent solution of the Schrödinger equations for electrons and holes and the Poisson equations at the presence of spatially varying quantum well potential due to the piezoelectric effect and local exchange-correlation potential is found. The one-dimensional Poisson equation contains the Hartree potential which includes the one-dimensional charge density for electrons and holes along the polarization field distribution. The three-dimensional Poisson equation contains besides the one-dimensional charge density for electrons and holes the exchange-correlation potential which is built on convolutions of a plane-wave part of wave functions in addition. The shifts of the Hartree valence band spectrums and the conduction band spectrum with respect to the flat band spectrums as well as the Hartree-Fock band spectrums with respect to the Hartree ones are found. An overlap integrals of the wave functions of holes and electron with taking into account besides the piezoelectric effects the exchange-correlation effects in addition is greater than an overlap integral of Hartree ones. The Hartree particles distribute greater on edges of quantum well than Hartree-Fock particles. It is found that an effective mass of heavy hole of Mg(0.27)Zn(0.73)O under biaxial strain is greater than an effective-mass of heavy hole of ZnO. It is calculated that an electron mass is less than a hole mass. It is found that the Bohr radius is grater than the localization range particle-hole pair, and the excitons may be spontaneously created.Schrödinger equation for pair of two massless Dirac particles when magnetic field is applied in Landau gauge is solved exactly. In this case the separation of center of mass and relative motion is obtained. Landau quantization $\epsilon=\pm\,B\sqrt{l}$ for pair of two Majorana fermions coupled via a Coulomb potential from massless chiral Dirac equation in cylindric coordinate is found. The root ambiguity in energy spectrum leads into Landau quantization for beelectron, when the states in which the one simultaneously exists are allowed. The tachyon solution with imaginary energy in Cooper problem ($\epsilon^{2}<0$) is found.

Symmetry and models of single-walled TiO2 nanotubes with rectangular morphology

Open Physics ◽  
2011 ◽  
Vol 9 (2) ◽  
Author(s):  
Robert Evarestov ◽  
Yuri Zhukovskii ◽  
Andrei Bandura ◽  
Sergei Piskunov
Keyword(s):  
Tio2 Nanotubes ◽  
Anatase Phase ◽  
Band Gaps ◽  
Symmetry Groups ◽  
1D Nanostructures ◽  
Exchange Correlation ◽  
Hartree Fock ◽  
Layer Structures ◽  
Structural And Electronic Properties ◽  
Tio2 Nts

AbstractThe formalism of line symmetry groups for one-periodic (1D) nanostructures with rotohelical symmetry has been applied for symmetry analysis of single-walled titania nanotubes (SW TiO2 NTs) formed by rolling up the stoichiometric two-periodic (2D) slabs of anatase structure. Either six- or twelve-layer (101) slabs have been cut from TiO2 crystal in a stable anatase phase. After structural optimization, the latter keeps the centered rectangular symmetry of initial slab slightly compressed along a direction coincided with large sides of elemental rectangles. We have considered two sets of SW TiO2 NTs with optimized six- and twelve-layer structures, which possess chiralities (−n, n) and (n, n) of anatase nanotubes. To analyze the structural and electronic properties of titania slabs and nanotubes, we have performed their ab initio LCAO calculations, using the hybrid Hartree-Fock/Kohn-Sham exchange-correlation functional PBE0. The band gaps (Δɛ gap) and strain energies (E strain) of six-layer nanotubes have been computed and analyzed as functions of NT diameter (D NT). As to models of 12-layer SW TiO2 NTs of both chiralities, their optimization results in structural exfoliation, i.e., the multi-walled structure should be rather formed in nanotubes with such a number of atomic layers.

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