Density-functional calculations of semiconductor properties using a semiempirical exchange-correlation functional

Rushton, Philip P.; Clark, Stewart J.; Tozer, David J.

doi:10.1103/physrevb.63.115206

Cited by 39 publications

(11 citation statements)

References 41 publications

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“…The pair of electrons with opposite spins occupies one orbital without dangling bond, whereby the material properties are mostly determined by the correlation part. The HCTH functional with an accurate correlation part has improved XC potentials, [44,48,49] which leads to accurate E g (D) values. Using the HCTH functional, the values a 0 = 5.474 and E g (1) = 1.24 eV were determined, which only differ from the experimental results of 5.431 [50] and 1.17 eV [51] by 0.79 % and 5.98 %, respectively.…”

Section: Computational Details and Methodsmentioning

confidence: 97%

Multi‐Field Effect on the Electronic Properties of Silicon Nanowires

et al. 2011

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The quantum confinement and electronic properties of silicon nanowires (SiNWs) under an external strain field ε and an electric field E-as well as both (ε plus E)-are systematically investigated using density functional theory. These two fields exist in working environments of integrated circuits. It is found that both ε and E lead to a drop of the band gap E(g)(ε,E) of the SiNWs. If both fields coexist, the interaction between ε and E causes that E(g)(ε,E) becomes orientation-dependent, which results from variations of both the conduction-band minimum and the valence-band maximum. The interaction is further illustrated by the density of states near the Fermi level and the eigenvalue of the highest occupied molecular orbital.

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Section: Computational Details and Methodsmentioning

confidence: 97%

Multi‐Field Effect on the Electronic Properties of Silicon Nanowires

et al. 2011

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“…They can be less successful when applied to systems that differ considerably from those in the fitting data, such as bulk semiconductors involving relatively heavy atoms. 12 For a hybrid functional ( 0) to give accurate orbitals and eigenvalues, it, too, must provide an accurate representation of v XC, (r). However, in this case v XC, (r) is not the conventional exchange-correlation potential since part of the exchange-correlation contribution to the Kohn-Sham operator is now accounted for in the non-multiplicative orbital exchange term.…”

Section: ͑3͒mentioning

confidence: 99%

Hybrid exchange-correlation functional determined from thermochemical data and ab initio potentials

Wilson¹,

Bradley²,

Tozer³

2001

The Journal of Chemical Physics

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525

340

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Multiplicative potentials, appropriate for adding to the non-multiplicative fractional orbital exchange term in the Kohn-Sham equations, are determined from correlated ab initio electron densities. The potentials are examined graphically and are used in conjunction with conventional thermochemical data to determine a new hybrid exchange-correlation functional, denoted B97-2. Calculations using B97-2 are compared with those from ͑a͒ the B97-1 functional ͓J. Chem. Phys. 109, 6264 ͑1998͔͒, which has the same functional form and fraction of orbital exchange, but was fitted to just thermochemical data; and ͑b͒ the widely used B3LYP functional ͓J. Chem. Phys. 98, 5648 ͑1993͔͒. B97-2 atomization energies are close to those from B97-1; total electronic energies and ionization potentials are less accurate, but remain an improvement over B3LYP. Molecular structures from all three functionals are comparable. Static isotropic polarizabilities improve from B3LYP to B97-1 to B97-2; the B97-2 functional underestimates experimental values, which is consistent with the neglect of zero-point vibrational corrections. NMR shielding constantsdetermined as the conventional second derivative of the electronic energy-improve from B3LYP to B97-1 to B97-2. Shieldings determined directly from these DFT electron densities using the recently proposed MKS approach ͓Chem. Phys. Lett. 337, 341 ͑2001͔͒ are two to three times more accurate than the conventional shieldings, and exhibit an analogous improvement across the three functionals. Classical reaction barriers for sixteen chemical reactions improve significantly from B3LYP to B97-1 to B97-2. The introduction of multiplicative potentials into semi-empirical hybrid functional development therefore appears beneficial.

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“…40 The original results using B97-2 were compared with those from the B97-1 ͑see Refs. If any ⌬SCF-based method is intended to provide accurate excitation energies between states of different symmetry, it is clear that it has first to give accurate enough orbitals and eigenvalues, it must therefore provide an accurate representation of the exchange-correlation potential; this has been previously attempted by explicitly introducing potential information into the fitting procedures.…”

Section: F Basic Differences Between Good and Badperforming Functionalsmentioning

confidence: 99%

Comparative studies of the spectroscopy of CuCl2: DFT versus standard ab initio approaches

Ramı́rez-Solı́s

Poteau

Vela

et al. 2005

The Journal of Chemical Physics

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The X2Pi g-2Sigma g+, X2Pi g-2Delta g, X2Pi g-2Sigma u+, X2Pi g-2Pi u transitions on CuCl2 have been studied using several exchange-correlation functionals from the various types of density functional theory (DFT) approaches like local density approximation (LDA), generalized gradient approximation (GGA), hybrid and meta-GGA. The results are compared with the experience and with those coming from the most sophisticated nondynamic and dynamic electronic correlation treatments using the same relativistic effective core potentials and especially developed basis sets to study the electronic structure of the five lowest states and the corresponding vertical and adiabatic transition energies. The calculated transition energies for three of the hybrid functionals (B3LYP, B97-2, and PBE0) are in very good agreement with the benchmark ab initio results and experimental figures. All of the other functionals largely overestimate the X2Pi g-2Sigma g+ and X2Pi g-2Delta g transition energies, many of them even placing the 2Delta g ligand field state above the charge transfer 2Pi u and 2Sigma u+ states. The relative weight of the Hartree-Fock exchange in the definition of the functional used appears to play a key role in the accurate description of the LambdaSSigma density defined by the orientation of the 3d hole (sigma, pi, or delta) on Cu in the field of both chlorine atoms, but no simple connection of this weight with the quality of the spectra has been found. Mulliken charges and spin densities are carefully analyzed; a possible link between the extent of spin density on the metal for the X2Pi g state and the performance of the various functionals was observed, suggesting that those that lead to the largest values (close to 0.65) are the ones that best reproduce these four transitions. Most functionals lead to a remarkably low ionicity for the three ligand field states even for the best performing functionals, compared to the complete active space (SCF) (21, 14) ab initio values. These findings show that not only large variational ab initio calculations can produce reliable spectroscopic results for extremely complex systems where delicate electronic correlation effects have to be carefully dealt with. However, those functionals that were recently shown to perform best for a series of molecular properties [J. Chem. Phys. 121 3405 (2004)] are not the ones that produce the best transition energies for this complex case.

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Density-functional calculations of semiconductor properties using a semiempirical exchange-correlation functional

Cited by 39 publications

References 41 publications

Multi‐Field Effect on the Electronic Properties of Silicon Nanowires

Multi‐Field Effect on the Electronic Properties of Silicon Nanowires

Hybrid exchange-correlation functional determined from thermochemical data and ab initio potentials

Comparative studies of the spectroscopy of CuCl2: DFT versus standard ab initio approaches

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