Single-Bond Torsional Potentials in Conjugated Systems:  A Comparison ofabInitioand Density Functional Results

1997 ◽  
Vol 101 (40) ◽  
pp. 7426-7433 ◽  
Author(s):  
Alfred Karpfen ◽  
Cheol Ho Choi ◽  
Miklos Kertesz
Keyword(s):  
Density Functional ◽  
Functional Results ◽  
Single Bond ◽  
Conjugated Systems ◽  
Torsional Potentials

Assessment of Conventional Density Functional Schemes for Computing the Dipole Moment and (Hyper)polarizabilities of Push−Pull π-Conjugated Systems†

2000 ◽  
Vol 104 (20) ◽  
pp. 4755-4763 ◽  
Author(s):  
Benoît Champagne ◽  
Eric A. Perpète ◽  
Denis Jacquemin ◽  
Stan J. A. van Gisbergen ◽  
Evert-Jan Baerends ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Density Functional ◽  
Conjugated Systems

Density Functional Theory Study of the Role of an Carbon–Oxygen Single Bond Group in the NO–Char Reaction

2018 ◽  
Vol 32 (7) ◽  
pp. 7734-7744 ◽  
Author(s):  
Tong Zhao ◽  
Wenli Song ◽  
Chuigang Fan ◽  
Songgeng Li ◽  
Peter Glarborg ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Single Bond ◽  
Density Functional Theory Study ◽  
Functional Theory

scholarly journals Machine learning the Hubbard U parameter in DFT+U using Bayesian optimization

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Maituo Yu ◽  
Shuyang Yang ◽  
Chunzhi Wu ◽  
Noa Marom
Keyword(s):  
Machine Learning ◽  
Transition Metal Oxides ◽  
Density Functional ◽  
Functional Results ◽  
Bayesian Optimization ◽  
Hybrid Functional ◽  
Band Structures ◽  
Local Exchange ◽  
Functional Theory ◽  
Exchange Correlation

AbstractWithin density functional theory (DFT), adding a Hubbard U correction can mitigate some of the deficiencies of local and semi-local exchange-correlation functionals, while maintaining computational efficiency. However, the accuracy of DFT+U largely depends on the chosen Hubbard U values. We propose an approach to determining the optimal U parameters for a given material by machine learning. The Bayesian optimization (BO) algorithm is used with an objective function formulated to reproduce the band structures produced by more accurate hybrid functionals. This approach is demonstrated for transition metal oxides, europium chalcogenides, and narrow-gap semiconductors. The band structures obtained using the BO U values are in agreement with hybrid functional results. Additionally, comparison to the linear response (LR) approach to determining U demonstrates that the BO method is superior.

Electronic Structure, Magnetism and Spin-Fluctuations in Fe-As Based Superconductors

2008 ◽  
Vol 1148 ◽  
Author(s):  
David Joseph Singh ◽  
Mao-Hua Du ◽  
Lijun Zhang ◽  
Alaska Subedi ◽  
Jiming An
Keyword(s):  
Electronic Structure ◽  
Fermi Surface ◽  
Density Functional ◽  
Density Wave ◽  
Spin Density Wave ◽  
Functional Results ◽  
Spin Fluctuations ◽  
Square Lattice ◽  
Itinerant Magnetism ◽  
Strong Spin

AbstractThe physical properties of the layered iron superconductors and related phases are discussed starting from first principles calculations. The electronic structure is described as that of metallic Fe2+ square lattice sheets with substantial direct Fe-Fe hopping and interactions with the neighboring anionic pnictogens or chalcogens. The materials have a semi-metallic band structure, and in particular the Fermi surface consists of small cylindrical electron sections centered at the zone corner, and compensating hole sections at the zone boundary. The density of states N(EF) is high placing the materials near itinerant magnetism in general, and furthermore the small Fermi surface sections are well nested leading to a tendency towards a spin density wave. Comparison of experimental and density functional results imply the presence of exceptionally strong spin fluctuations in these materials. Superconductivity is discussed within this context.

High-order correlation effects on dynamic hyperpolarizabilities and their geometric derivatives: A comparison with density functional results

2006 ◽  
Vol 124 (11) ◽  
pp. 114101 ◽  
Author(s):  
Magdalena Pecul ◽  
Filip Pawłowski ◽  
Poul Jørgensen ◽  
Andreas Köhn ◽  
Christof Hättig
Keyword(s):  
Density Functional ◽  
Functional Results ◽  
High Order ◽  
Correlation Effects ◽  
High Order Correlation

scholarly journals Time-dependent Density Functional Results for the Dynamic Hyperpolarizability ofC60

1997 ◽  
Vol 78 (16) ◽  
pp. 3097-3100 ◽  
Author(s):  
S. J. A. van Gisbergen ◽  
J. G. Snijders ◽  
E. J. Baerends
Keyword(s):  
Density Functional ◽  
Functional Results ◽  
Time Dependent ◽  
Dependent Density
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