Molecular and Solid-State Tests of Density Functional Approximations: LSD, GGAs, and Meta-GGAs
نویسندگان
چکیده
Results from numerical tests of nine approximate exchange]correlation energy functionals are reported for various systems—atoms, molecules, surfaces, and Ž . bulk solids. The functional forms can be divided into three categories: 1 the local spin Ž . Ž . Ž . Ž . density LSD approximation, 2 generalized gradient approximations GGAs , and 3 meta-GGAs. In addition to the spin densities and their first gradients, the input to a meta-GGA includes other semilocal information such as Laplacians of the spin densities or orbital kinetic energy densities. We present a way to visualize meta-GGA nonlocality which generalizes that for GGA nonlocality, and which stresses the different meta-GGA descriptions of iso-orbital and orbital overlap regions of space. While some of the tested approximations were constructed semiempirically with many parameters fitted to chemical data, others were constructed to incorporate key properties of the exact exchange]correlation energy. The latter functionals perform well for both small and extended systems, with the best performance achieved by a meta-GGA which recovers the correct gradient expansion. While the semiempirical functionals can achieve high accuracy for atoms and molecules, they are typically less accurate for surfaces and solids. Q 1999 John Wiley & Sons, Inc. Int J Quant Chem 75: 889]909, 1999
منابع مشابه
Semilocal density functional obeying a strongly tightened bound for exchange.
Because of its useful accuracy and efficiency, density functional theory (DFT) is one of the most widely used electronic structure theories in physics, materials science, and chemistry. Only the exchange-correlation energy is unknown, and needs to be approximated in practice. Exact constraints provide useful information about this functional. The local spin-density approximation (LSDA) was the ...
متن کاملUnderstanding band gaps of solids in generalized Kohn-Sham theory.
The fundamental energy gap of a periodic solid distinguishes insulators from metals and characterizes low-energy single-electron excitations. However, the gap in the band structure of the exact multiplicative Kohn-Sham (KS) potential substantially underestimates the fundamental gap, a major limitation of KS density-functional theory. Here, we give a simple proof of a theorem: In generalized KS ...
متن کاملNonseparable exchange-correlation functional for molecules, including homogeneous catalysis involving transition metals.
The goal of this work is to develop a gradient approximation to the exchange-correlation functional of Kohn-Sham density functional theory for treating molecular problems with a special emphasis on the prediction of quantities important for homogeneous catalysis and other molecular energetics. Our training and validation of exchange-correlation functionals is organized in terms of databases and...
متن کاملBenchmark Study of the Performance of Density Functional Theory for Bond Activations with (Ni,Pd)-Based Transition-Metal Catalysts
The performance of 23 density functionals, including one LDA, four GGAs, three meta-GGAs, three hybrid GGAs, eight hybrid meta-GGAs, and ten double-hybrid functionals, was investigated for the computation of activation energies of various covalent main-group single bonds by four catalysts: Pd, PdCl(-), PdCl2, and Ni (all in the singlet state). A reactant complex, the barrier, and reaction energ...
متن کاملThermally-assisted-occupation density functional theory with generalized-gradient approximations.
We extend the recently proposed thermally-assisted-occupation density functional theory (TAO-DFT) [J.-D. Chai, J. Chem. Phys. 136, 154104 (2012)] to generalized-gradient approximation (GGA) exchange-correlation density functionals. Relative to our previous TAO-LDA (i.e., the local density approximation to TAO-DFT), the resulting TAO-GGAs are significantly superior for a wide range of applicatio...
متن کامل