Nonempirical density-functional theory for van der Waals interactions

2010 ◽  
Vol 88 (11) ◽  
pp. 1057-1062 ◽  
Author(s):  
Axel D. Becke ◽  
Alya A. Arabi ◽  
Felix O. Kannemann
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Van Der Waals ◽  
Van Der Waals Complexes ◽  
Basis Sets ◽  
Generalized Gradient ◽  
Dispersion Energy ◽  
Functional Theory ◽  
Grid Based

In previous work, Kannemann and Becke [ J. Chem. Theory Comput. 5, 719 (2009) and J. Chem. Theory Comput. 6, 1081 (2010) ] have demonstrated that the generalized gradient approximations (GGAs) of Perdew and Wang for exchange [Phys. Rev. B 33, 8800 (1986)] and Perdew, Burke, and Ernzerhof for correlation [Phys. Rev. Lett. 77, 3865 (1996)] , plus the dispersion density functional of Becke and Johnson [J. Chem. Phys. 127, 154108 (2007)] , comprise a nonempirical density-functional theory of high accuracy for thermochemistry and van der Waals complexes. The theory is nonempirical except for two universal cutoff parameters in the dispersion energy. Our calculations so far have been grid-based and have employed the local density approximation (LDA) for the orbitals. In this work, we employ orbitals from self-consistent GGA calculations using Gaussian basis sets. The results, on a benchmark set of 65 van der Waals complexes, are similar to our grid-based post-LDA results. This work sets the stage for van der Waals force computations and geometry optimizations.

Density Functional Theory Approach for Muon Sites Estimation in Mn3Sn

2021 ◽  
Vol 1028 ◽  
pp. 199-203
Author(s):  
Fiqhri Heda Murdaka ◽  
Edi Suprayoga ◽  
Abdul Muizz Pradipto ◽  
Kohji Nakamura ◽  
Agustinus Agung Nugroho
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Full Potential ◽  
Theory Approach ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Electrostatic Potential Calculation ◽  
A Site ◽  
Linearized Augmented Plane Wave

We report the estimation of muon sites inside Mn3Sn using density functional theory based on the full-potential linearized augmented plane wave (FLAPW) calculation. Our calculation shows that the Perdew–Burke–Ernzerhof (PBE) Generalized-Gradient Approximation (GGA) functional is closer to the experimental structure compared to the von Barth-Hedin Local Density Approximation (LDA)-optimized geometry. The PBE GGA is therefore subsequently used in FLAPW post-calculation for the electrostatic potential calculation to find the local minima position as a guiding strategy for estimating the muon site. Our result reveals at least two muon sites of which one is placed at the center between two Mn-Sn triangular layers (A site) and the other at the trigonal prismatic site of Sn atom (B site). The total energy of Mn3Sn system in the presence of muon at A site or B site are compared and we find that A site is a more favorable site for muon to stop.

Electronic and geometric structure of AuxCuy clusters studied by density functional theory

2014 ◽  
Vol 25 (06) ◽  
pp. 1450011 ◽  
Author(s):  
Y. Kadioglu ◽  
O. Üzengi Aktürk ◽  
M. Tomak
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Local Density ◽  
Three Dimensional ◽  
Binding Energies ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

We have determined the stable structures of Au Cu n, Au 2 Cu n, Au 3 Cu n and Au x Cu 8-x clusters. It has been observed that Au Cu n, Au 2 Cu n and Au 3 Cu n systems have two-dimensional (2D) structures up to six atoms and they become three-dimensional (3D) afterwards. Au x Cu 8-x clusters favor 3D structures till the Au 7 Cu 1 cluster. We have found a lowest energy isomer of Au 6 Cu 2 from the literature. Bond lengths, binding energies, density of states (DOS), highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO-LUMO) gaps, ionization potential (IP) and electron affinity (EA) have been calculated for these structures using the first principles density functional theory (DFT) within the generalized gradient approximation (GGA) and the local density approximation (LDA). Generally, we have observed the overlap between s electrons of Cu and p electrons of Au near the Fermi level. Charge transfers are calculated by using the Löwdin analysis. It is observed that one Cu atom does not significantly modify the clusters which have more gold atoms. It is also seen that these clusters generally have nonmagnetic properties and results are consistent with the hybridization between s and d orbitals of Au in Au x Cu 8-x clusters.

A density functional theory study of the free radicals NH2, NF2, NCl2, PH2, PF2, and PCl2

1994 ◽  
Vol 72 (3) ◽  
pp. 695-704 ◽  
Author(s):  
Maggie A. Austen ◽  
Leif A. Eriksson ◽  
Russell J. Boyd
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Basis Set ◽  
Basis Sets ◽  
Functional Theory ◽  
Unpaired Spin ◽  
Non Local ◽  
Local Potentials ◽  
Spin Densities

The linear combination of Gaussian-type orbitals–density functional theory (LCGTO–DFT) approach is used to study geometries and hyperfine structures of a set of neutral radicals. Each of the title molecules is investigated by means of local density approximation calculations, and using the Becke–Perdew and Perdew–Wang–Perdew corrections to the exchange and correlation functionals. The effects of local vs. non-local potentials and of various basis sets are investigated. Total densities and unpaired spin densities are compared. The isotropic couplings are found to be very dependent on the type of exchange functional used, whereas the anisotropic couplings are relatively insensitive to the choice of basis set and functional. In most cases, the Perdew–Wang exchange corrections provide isotropic couplings in satisfactory agreement with experiment.

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