scholarly journals Semi-local density functional for the exchange-correlation energy of electrons in two dimensions

2010 ◽  
Vol 110 (12) ◽  
pp. 2308-2314 ◽  
Author(s):  
E. Räsänen ◽  
S. Pittalis ◽  
J. G. Vilhena ◽  
M. A. L. Marques
Keyword(s):  
Density Functional ◽  
Correlation Energy ◽  
Local Density ◽  
Two Dimensions ◽  
Exchange Correlation ◽  
Local Density Functional

scholarly journals COMPARISON OF DENSITY FUNCTIONAL APPROXIMATIONS IN THE JELLIUM MODEL FOR METAL CLUSTERS

2001 ◽  
Vol 15 (10n11) ◽  
pp. 1724-1727 ◽  
Author(s):  
CARLOS FIOLHAIS ◽  
L. M. ALMEIDA
Keyword(s):  
Monte Carlo ◽  
Density Functional ◽  
Alkali Metals ◽  
Correlation Energy ◽  
Local Density ◽  
Jellium Model ◽  
Generalized Gradient ◽  
Exchange Correlation ◽  
Generalized Gradient Approximation ◽  
Exchange And Correlation

We calculated the exchange, correlation and total energies of clusters of alkali metals with N=1-150 atoms in the spherical jellium model. The calculations were made using the Kohn-Sham method with exchange and correlation energies evaluated in the meta-generalized gradient approximation (MGGA), proposed by J. P. Perdew, S. Kurth, A. Zupan and P. Blaha, in the generalized gradient approximation (GGA) of J. P. Perdew, K. Burke and M. Ernzerhof, and in the Local Density Approximation (LDA). We evaluated the relative deviations of MGGA and GGA energies with respect to LDA. Exchange energies of MGGA and GGA are more negative than the LDA exchange energy and become closer to this as the cluster size increases. On the other hand, the GGA and MGGA correlation energies, which are almost identical, are less negative than LDA. The deviations of GGA and MGGA exchange-correlation energies with respect to LDA are smaller than those of the exchange and correlation energies separately. For clusters with 18 and 20 atoms we have compared our jellium results with Variational and Diffusion Monte-Carlo results. Errors of LDA for exchange and correlation tend to cancel so that the total exchange-correlation energy is close to the Monte-Carlo results. Similar cancellations occur with GGA and MGGA. We also examined the validity of the liquid drop model.

The Si Vacancy: An Example of a Pressure-Sensitive Jahn-Teller System

1992 ◽  
Vol 291 ◽  
Author(s):  
Eugen Tarnow
Keyword(s):  
Density Functional ◽  
Correlation Energy ◽  
Local Density ◽  
Electronic Correlation ◽  
Functional Theory ◽  
Breathing Mode ◽  
Pressure Sensitive ◽  
Jahn Teller ◽  
Local Density Functional Theory ◽  
Local Density Functional

ABSTRACTWe calculate the trends in the Jahn-Teller (JT) parameters of the Si vacancy as a function of the breathing mode coordinate. Using ab-initio local-density-functional theory and Hellman--Feynman forces we find the couplings between the JT modes and the breathing mode to be significant. Since the breathing mode coordinate is very sensitive to pressure we predict a pressure-sensitive JT contribution to the effective electronic correlation energy U. Furthermore we find that the tetragonal JT energy increasingly dominates over the trigonal energy as the breathing coordinate decreases due to a softening of the tetragonal spring constant.

Density functionals beyond the local approximation

1991 ◽  
Vol 334 (1635) ◽  
pp. 481-490 ◽  
Keyword(s):  
Density Functional ◽  
Correlation Energy ◽  
Local Density ◽  
Local Approximation ◽  
Density Functionals ◽  
Current Effort ◽  
Functional Theory ◽  
Quasi Particle ◽  
Exchange Correlation ◽  
The Density Functional Theory

A review of the current effort in improvement over the local density approximation is given. Within the density functional theory, the exchange-correlation energy and potential may be unambiguously defined. Based on the field theoretical expressions for them, approximations for classes of systems and approxim ate evaluations for specific solids are critically reviewed. Further lines of development are discussed. Relation to the quasi-particle energies is explored.

Exchange-Correlation Energy Densities and Response Potentials: Connection Between Two Definitions and Analytical Model for the Strong-Coupling Limit of a Stretched Bond

2019 ◽  
Author(s):  
S. Giarrusso ◽  
Paola Gori-Giorgi
Keyword(s):  
Density Functional Theory ◽  
Strong Coupling ◽  
Density Functional ◽  
Correlation Energy ◽  
Order Term ◽  
Strong Coupling Limit ◽  
Local Form ◽  
Coupling Constant ◽  
Functional Theory ◽  
Exchange Correlation

We analyze in depth two widely used definitions (from the theory of conditional probablity amplitudes and from the adiabatic connection formalism) of the exchange-correlation energy density and of the response potential of Kohn-Sham density functional theory. We introduce a local form of the coupling-constant-dependent Hohenberg-Kohn functional, showing that the difference between the two definitions is due to a corresponding local first-order term in the coupling constant, which disappears globally (when integrated over all space), but not locally. We also design an analytic representation for the response potential in the strong-coupling limit of density functional theory for a model single stretched bond.<br>

Magnetic Properties of Embedded Rh Clusters in Ni Matrix

1995 ◽  
Vol 384 ◽  
Author(s):  
Zhi-Qiang Li ◽  
Yuichi Hashi ◽  
Jing-Zhi Yu ◽  
Kaoru Ohno ◽  
Yoshiyuki Kawazoe
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Magnetic Moments ◽  
Functional Formalism ◽  
Rhodium Clusters ◽  
Spin Polarized ◽  
Local Density Functional

ABSTRACTThe electronic structure and magnetic properties of rhodium clusters with sizes of 1 - 43 atoms embedded in the nickel host are studied by the first-principles spin-polarized calculations within the local density functional formalism. Single Rh atom in Ni matrix is found to have magnetic moment of 0.45μB. Rh13 and Rhl 9 clusters in Ni matrix have lower magnetic moments compared with the free ones. The most interesting finding is tha.t Rh43 cluster, which is bulk-like nonmagnetic in vacuum, becomes ferromagnetic when embedded in the nickel host.

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