The logarithmic singularity of the Lindhard linear response function plays an important role in various phenomena, such as the long-range Friedel oscillations and Kohn anomaly in phonon dispersion. Such a weak singularity cannot be captured by the known gradient expansion of the kinetic energy (KE), but it can be somewhat mimicked by the second-order gradient singularity expansion (GSE2) developed in this work. We show that the GSE2 Pauli KE potential of atoms, computed with the Kohn-Sham density, is remarkably accurate, being the best possible approximation provided by any second-order KE gradient expansion. Next, we study the utility of GSE2 for orbital-free density functional theory, and we prove that the GSE2-based KE functionals give an important and systematic improvement over other popular KE functionals.
Semilocal properties of the Pauli kinetic potential
Constantin L. A.
2019
Abstract
The logarithmic singularity of the Lindhard linear response function plays an important role in various phenomena, such as the long-range Friedel oscillations and Kohn anomaly in phonon dispersion. Such a weak singularity cannot be captured by the known gradient expansion of the kinetic energy (KE), but it can be somewhat mimicked by the second-order gradient singularity expansion (GSE2) developed in this work. We show that the GSE2 Pauli KE potential of atoms, computed with the Kohn-Sham density, is remarkably accurate, being the best possible approximation provided by any second-order KE gradient expansion. Next, we study the utility of GSE2 for orbital-free density functional theory, and we prove that the GSE2-based KE functionals give an important and systematic improvement over other popular KE functionals.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
