Augmented-wave pseudopotentials

Floizwarth N A W, Matthews G E, Dunning R B, Tackett A R and Zeng Y 1997 Comparison of the projector augmented-wave, pseudopotential and linearized augmented-plane-wave formalisms for density-functional calculations of solids Phys. Rev. B 55 2005... 

The projector augmented-wave (PAW) DFT method was invented by Blochl to generalize both the pseudopotential and the LAPW DFT teclmiques [M]- PAW, however, provides all-electron one-particle wavefiinctions not accessible with the pseudopotential approach. The central idea of the PAW is to express the all-electron quantities in tenns of a pseudo-wavefiinction (easily expanded in plane waves) tenn that describes mterstitial contributions well, and one-centre corrections expanded in tenns of atom-centred fiinctions, that allow for the recovery of the all-electron quantities. The LAPW method is a special case of the PAW method and the pseudopotential fonnalism is obtained by an approximation. Comparisons of the PAW method to other all-electron methods show an accuracy similar to the FLAPW results and an efficiency comparable to plane wave pseudopotential calculations [, ]. PAW is also fonnulated to carry out DFT dynamics, where the forces on nuclei and wavefiinctions are calculated from the PAW wavefiinctions. (Another all-electron DFT molecular dynamics teclmique using a mixed-basis approach is applied in [84].)... 

Kresse, G. and Joubert, D. (1999) From ultrasoft pseudopotentials to the projector augmented-wave method. Physical Review B - Condensed Matter, 59, 1758-1775. 

G. Kresse and D. Joubert, From Ultrasoft Pseudopotentials to the Projector Augmented-Wave Method, Phys. Rev. B 59 (1999), 1758. 

The local density approximation (LDA) and GGA within a plane-wave pseudopotential method was used in Ishibashi and Kohyama (2000) while DFT within the linearized augmented plane wave (LAPW) approach was employed in Sing et al. (2003b). 

Note A/B implies A grown or strained to B and vice versa. A B implies no growth direction or explicit strain dependence, i.e. natural. ) T = theoretical E = experimental AVL = average lattice XPS = X-ray photoelectron spectroscopy PL = photoluminescence CL = cathodoluminescence UPS = ultraviolet photoelectron spectroscopy LMTO = linear muffin tin orbital method LAPW = linearised augmented plane wave method PWP = plane wave pseudopotential method VCA = virtual crystal approximation. 

PAW (projector augmented-wave) is a method designed to have the flexibility of FLAPW methods with the simplicity of pseudopotential methods. In the PAW method, all-electron one electron wave functions, are derived from pseudo-one electron wave functions, P , where n refers to the wth band by means of a linear transformation... 

Most plane wave calculations use ultrasoft pseudopotentials (USPP),15,28 which describe the core electrons of atoms in a mathematically efficient form that greatly reduces the computational cost associated with heavy atoms. An increasing number of calculations used the projector augmented wave (PAW) approach instead.28 In most circumstances where both approaches can be used, the differences between USPP and PAW calculations are minor. Some exceptions to this observation include transition metals with large magnetic moments (e.g., Fe) and alkali metals.28... 

The above approaches, especially the various kinds of pseudopotential and linearized augmented-wave methods, have become well-established tools within theoretical solid-state science. During the last decade, new approaches have been developed, which promise both accuracy and even faster performance. Here are two developments which show high potential because they enable one to describe the chemistry and physics of complex and, in particular, large systems. 

At first sight, the pseudopotential approach and the different partial-wave methods do not seem to have very much in common. In the first approach, the inner, atom-like wave functions are discarded altogether and replaced by a much weaker potential. In the second group, the outer wave function augments exactly these atom-like partial waves. The projector-augmented wave (PAW) method by Blochl [237], however, combines the two ideas into a unified electronic-structure method. Without going into detail, the PAW method can be looked upon as a pseudopotential method in which the pseudopotential instantaneously adapts to the electronic environment. This is because the PAW method is, in fact, a complete all-electron method, and its internal pseu-... 

Many periodic codes are mentioned in the literature, mostly based on either a plane waves basis set and pseudopotentials or projector-augmented waves. Some of this software can be purchased, and the rest is available through collaboration with the main development team or downloadable... 

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