scholarly journals Massively parallel, linear-scaling Hartree-Fock exchange and hybrid exchange-correlation functionals with plane-wave basis set accuracy

2021 ◽  
Author(s):  
Jacek Dziedzic ◽  
James Christopher Womack ◽  
Rozh Ali ◽  
Chris-Kriton Skylaris
Keyword(s):  
Plane Wave ◽  
Basis Set ◽  
Massively Parallel ◽  
Linear Scaling ◽  
Exchange Correlation ◽  
Hartree Fock

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 Dispersion Corrected r2SCAN Based Global Hybrid Functionals: r2SCANh, r2SCAN0, and r2SCAN50

2021 ◽  
Author(s):  
Markus Bursch ◽  
Hagen Neugebauer ◽  
Sebastian Ehlert ◽  
Stefan Grimme
Keyword(s):  
Structural Parameters ◽  
Main Group ◽  
Basis Set ◽  
Generalized Gradient ◽  
Exchange Correlation ◽  
Hartree Fock ◽  
Exact Exchange ◽  
Hybrid Functionals ◽  
London Dispersion

The re-regularized semilocal meta generalized gradient approximation (meta-GGA) exchange-correlation functional r2SCAN [J. W. Furness, A. D. Kaplan, J. Ning, J. P. Perdew, and J. Sun, J. Phys. Chem. Lett. 11, 8208–8215 (2020)] is used to create the three global hybrid functionals with varying admixtures of Hartree–Fock exact exchange (HFX). The resulting exchange-correlation functionals r2SCANh (10% HFX), r2SCAN0 (25% HFX), and r2SCAN50 (50%HFX) are combined with the recent semi-classical D4 London dispersion correction. The new functionals are assessed for molecular geometries, general main-group, and metalorganic thermochemistry at 26 comprehensive benchmark sets including such as the large GMTKN55, ROST61, and IONPI19 sets. It is shown that a moderate admixture of HFX leads to overall mean percentual improvements of −11 (r2SCANh-D4), −16 (r2SCAN0-D4), and −1% (r2SCAN50-D4) regarding thermochemistry compared to the parental meta-GGA. For organometallic reaction energies and barriers, r2SCAN0-D4 even yields a mean improvement of −35%. The computation of structural parameters does not systematically profit from HFX admixture. Overall, the most promising combination r2SCAN0-D4 performs well for both main-group and organometallic thermochemistry. It yields deviations better or on par with other very well-performing global hybrid functionals such as PW6B95-D4 or PBE0-D4. Regarding systems prone to self-interaction errors (SIE4x4), r2SCAN0-D4 shows reasonable performance, reaching the quality of the range-separated ωB97X-V functional. Accordingly, r2SCAN0-D4 in combination with a sufficiently converged basis set (def2-QZVP(P)) represents a robust and reliable choice for general use in the calculation of thermochemical properties of both, main-group and organometallic chemistry.

Calculations of Atomic and Electronic Structure for (100) Surfaces of SrTiO3 Perovskite

2002 ◽  
Vol 718 ◽  
Author(s):  
R. I. Eglitis ◽  
E. Heifets ◽  
E. A. Kotomin ◽  
G. Borstel
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Computer Code ◽  
Basis Set ◽  
Surface Relaxation ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Hartree Fock ◽  
Atomic And Electronic Structure

AbstractWe present and discuss main results of the calculations for the surface relaxation and rumpling of SrTiO3 surfaces with TiO2 and SrO terminations using a wide variety of methods of modern computational physics and chemistry, including the shell model (SM) and ab initio methods based on Hartree-Fock (HF) and Density Functional Theory (DFT). The HF and DFT formalisms with different exchange-correlation functionals are implemented into Crystal-98 computer code using a Gaussian-type basis set. We demonstrate that a hybrid B3PW formalism gives the best results for the bulk SrTiO3 properties. Results are compared with previous ab initio plane-wave LDA calculations and LEED experiments. Our calculations demonstrate an increase of the covalency effects between Ti and O atoms near the surface.

Role of Exchange-Correlation Functional in Bulk Bismuth

2020 ◽  
Vol 978 ◽  
pp. 446-453
Author(s):  
Soumyasree Jena ◽  
Sanjoy Datta
Keyword(s):  
Band Structure ◽  
Plane Wave ◽  
Density Functional ◽  
Ambient Pressure ◽  
Basis Set ◽  
Hole Pocket ◽  
Exchange Correlation ◽  
Structure Density ◽  
Energy Convergence ◽  
Electron Pocket

Presence of Bismuth (Bi) leads to topologically nontrivial band structure in many materials, especially in topological insulators. Traditionally Bi is known to be a semimetal but, quite surprisingly, in a recent experiment bulk Bi has been found to be a superconductor below 0.53 mK at ambient pressure. In order to have a closer look at the electronic properties of bulk Bi in the wake of this unexpected experimental evidence of superconducting phase, we have performed density-functional-theory (DFT) based first principle calculations using plane-wave basis set and with suitable ionic pseudopotentials. We have computed the band structure, density of states and Fermi surfaces for two different type of exchange-correlation (XC) functionals, namely Perdew-Zunger (PZ) and Perdew-Burke-Ernzerhof (PBE) type. Each of these XC functional has been considered without and with spin orbit (SO) interaction. After carefully examining the energy-convergence with respect to plane wave basis set and k-points in each case, the band structure has been calculated along the path Γ-L-T-Γ. Without SO coupling, electron pocket is found near ‘L’ and exactly at ‘Г’ and hole pocket is at ‘T’ for PZ type XC functional, while in the case of PBE-type electron pocket is found exactly at ‘L’ but the hole pocket to be near to ‘T’. With SO coupling, in PZ-type, electron pocket remains at same position, but hole pocket appears only at ‘Г’ point. Finally, when SO coupling is taken into account along with PBE-type XC functional electrons and holes are found at ‘L’ and at ‘T’ respectively. Furthermore, in this case we also observe an increase in the number of holes at ‘T’.

The Perdew–Burke–Ernzerhof exchange-correlation functional applied to the G2-1 test set using a plane-wave basis set

2005 ◽  
Vol 122 (23) ◽  
pp. 234102 ◽  
Author(s):  
Joachim Paier ◽  
Robin Hirschl ◽  
Martijn Marsman ◽  
Georg Kresse
Keyword(s):  
Plane Wave ◽  
Basis Set ◽  
Test Set ◽  
Exchange Correlation

Evaluating Transition Metal Barrier Heights with the Latest DFT Exchange–Correlation Functionals – the MOBH35 Benchmark Dataset

2019 ◽  
Author(s):  
Mark Iron ◽  
Trevor Janes
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Computational Cost ◽  
Basis Set ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Barrier Heights ◽  
Complete Basis Set ◽  
Complete Basis Set Limit ◽  
Hybrid Functionals

A new database of transition metal reaction barrier heights – MOBH35 – is presented. Benchmark energies (forward and reverse barriers and reaction energy) are calculated using DLPNO-CCSD(T) extrapolated to the complete basis set limit using a Weizmann1-like scheme. Using these benchmark energies, the performance of a wide selection of density functional theory (DFT) exchange–correlation functionals, including the latest from the Truhlar and Head-Gordon groups, is evaluated. It was found, using the def2-TZVPP basis set, that the ωB97M-V (MAD 1.8 kcal/mol), ωB97X-V (MAD 2.1 kcal/mol) and SCAN0 (MAD 2.1 kcal/mol) hybrid functionals are recommended. The double-hybrid functionals PWPB95 (MAD 1.6 kcal/mol) and B2K-PLYP (MAD 1.8 kcal/mol) did perform slightly better but this has to be balanced by their increased computational cost.

scholarly journals Linear scaling calculation of maximally localized Wannier functions with atomic basis set

2006 ◽  
Vol 124 (23) ◽  
pp. 234108 ◽  
Author(s):  
H. J. Xiang ◽  
Zhenyu Li ◽  
W. Z. Liang ◽  
Jinlong Yang ◽  
J. G. Hou ◽  
...  
Keyword(s):  
Basis Set ◽  
Linear Scaling ◽  
Wannier Functions
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