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6CCVD Research

Nonlocal kinetic energy functionals by functional integration

At a Glance

Section titled ā€œAt a Glanceā€
MetadataDetails
Publication Date2018-05-10
JournalThe Journal of Chemical Physics
AuthorsWenhui Mi, Alessandro Genova, Michele Pavanello
InstitutionsRutgers, The State University of New Jersey
Citations77

Abstract

Section titled ā€œAbstractā€

Since the seminal studies of Thomas and Fermi, researchers in the Density-Functional Theory (DFT) community are searching for accurate electron density functionals. Arguably, the toughest functional to approximate is the noninteracting kinetic energy, Ts[Ļ], the subject of this work. The typical paradigm is to first approximate the energy functional and then take its functional derivative, Ī“Ts[Ļ]Ī“Ļ(r), yielding a potential that can be used in orbital-free DFT or subsystem DFT simulations. Here, this paradigm is challenged by constructing the potential from the second-functional derivative via functional integration. A new nonlocal functional for Ts[Ļ] is prescribed [which we dub Mi-Genova-Pavanello (MGP)] having a density independent kernel. MGP is constructed to satisfy three exact conditions: (1) a nonzero ā€œKinetic electronā€ arising from a nonzero exchange hole; (2) the second functional derivative must reduce to the inverse Lindhard function in the limit of homogenous densities; (3) the potential is derived from functional integration of the second functional derivative. Pilot calculations show that MGP is capable of reproducing accurate equilibrium volumes, bulk moduli, total energy, and electron densities for metallic (body-centered cubic, face-centered cubic) and semiconducting (crystal diamond) phases of silicon as well as of III-V semiconductors. The MGP functional is found to be numerically stable typically reaching self-consistency within 12 iterations of a truncated Newton minimization algorithm. MGPā€™s computational cost and memory requirements are low and comparable to the Wang-Teter nonlocal functional or any generalized gradient approximation functional.

Tech Support

Section titled ā€œTech Supportā€

Original Source

Section titled ā€œOriginal Sourceā€

References

Section titled ā€œReferencesā€
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