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Journal ArticleDOI

From ultrasoft pseudopotentials to the projector augmented-wave method

15 Jan 1999-Physical Review B (American Physical Society)-Vol. 59, Iss: 3, pp 1758-1775
TL;DR: In this paper, the formal relationship between US Vanderbilt-type pseudopotentials and Blochl's projector augmented wave (PAW) method is derived and the Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional.
Abstract: The formal relationship between ultrasoft (US) Vanderbilt-type pseudopotentials and Bl\"ochl's projector augmented wave (PAW) method is derived. It is shown that the total energy functional for US pseudopotentials can be obtained by linearization of two terms in a slightly modified PAW total energy functional. The Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional. A simple way to implement the PAW method in existing plane-wave codes supporting US pseudopotentials is pointed out. In addition, critical tests are presented to compare the accuracy and efficiency of the PAW and the US pseudopotential method with relaxed core all electron methods. These tests include small molecules $({\mathrm{H}}_{2}{,\mathrm{}\mathrm{H}}_{2}{\mathrm{O},\mathrm{}\mathrm{Li}}_{2}{,\mathrm{}\mathrm{N}}_{2}{,\mathrm{}\mathrm{F}}_{2}{,\mathrm{}\mathrm{BF}}_{3}{,\mathrm{}\mathrm{SiF}}_{4})$ and several bulk systems (diamond, Si, V, Li, Ca, ${\mathrm{CaF}}_{2},$ Fe, Co, Ni). Particular attention is paid to the bulk properties and magnetic energies of Fe, Co, and Ni.
Citations
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Journal ArticleDOI
TL;DR: A first-principles study of hydrogen storage media consisting of calcium atoms and graphene-based nanostructures finds that Ca atoms prefer to be individually adsorbed on the zigzag edge of graphene with a Ca-Ca distance of 10 A without clustering of the Ca atoms.
Abstract: We report a first-principles study of hydrogen storage media consisting of calcium atoms and graphene-based nanostructures. We find that Ca atoms prefer to be individually adsorbed on the zigzag edge of graphene with a Ca−Ca distance of 10 A without clustering of the Ca atoms, and up to six H2 molecules can bind to a Ca atom with a binding energy of ∼0.2 eV/H2. A Ca-decorated zigzag graphene nanoribbon (ZGNR) can reach the gravimetric capacity of ∼5 wt % hydrogen. We also consider various edge geometries of the graphene for Ca dispersion.

321 citations

Journal ArticleDOI
TL;DR: An ideal candidate material, Mo2C monolayer, with not only required large capacity but also high stability and mobility by means of first-principles calculations is reported, highlighting the promise of Mo2Cs as an appealing anode material for both lithium-ion and sodium-ion batteries.
Abstract: Identifying suitable electrodes materials with desirable electrochemical properties is urgently needed for the next generation of renewable energy technologies. Here we report an ideal candidate material, Mo2C monolayer, with not only required large capacity but also high stability and mobility by means of first-principles calculations. After ensuring its dynamical and thermal stabilities, various low energy Li and Na adsorption sites are identified, and the electric conductivity of the host material is also maintained. The calculated minor diffusion barriers imply a high mobility and cycling ability of Mo2C. In addition, the Li-adsorbed Mo2C monolayer possesses a high theoretical capacity of 526 mAh·g–1 and a low average electrode potential of 0.14 eV. Besides, we find that the relatively low capability of Na-adsorbed Mo2C (132 mAh·g–1) arises from the proposed competition mechanism. These results highlight the promise of Mo2C monolayer as an appealing anode material for both lithium-ion and sodium-ion b...

320 citations

Journal ArticleDOI
TL;DR: In situ scanning tunneling microscopy studies of graphene growth on Pd(111) during ethylene deposition at temperatures between 723 and 1023 K point to the possibility of preparing semiconducting graphene layers for future carbon-based nanoelectronic devices via direct deposition onto strongly interacting substrates.
Abstract: We report in situ scanning tunneling microscopy studies of graphene growth on Pd(111) during ethylene deposition at temperatures between 723 and 1023 K. We observe the formation of monolayer graphene islands, 200-2000 A in size, bounded by Pd surface steps. Surprisingly, the topographic image contrast from graphene islands reverses with tunneling bias, suggesting a semiconducting behavior. Scanning tunneling spectroscopy measurements confirm that the graphene islands are semiconducting, with a band gap of 0.3 +/- 0.1 eV. On the basis of density functional theory calculations, we suggest that the opening of a band gap is due to the strong interaction between graphene and the Pd substrate. Our findings point to the possibility of preparing semiconducting graphene layers for future carbon-based nanoelectronic devices via direct deposition onto strongly interacting substrates.

320 citations

Journal ArticleDOI
TL;DR: An ab initio pseudopotential method based on density functional theory, generalized gradient corrections to exchange and correlation, and projector-augmented waves is used to investigate structural, energetical, electronic, and optical properties of the ground-state phases rocksalt, cesium chloride, zinc blende, and wurtzite.
Abstract: An ab initio pseudopotential method based on density functional theory, generalized gradient corrections to exchange and correlation, and projector-augmented waves is used to investigate structural, energetical, electronic, and optical properties of $\mathrm{MgO}$, $\mathrm{ZnO}$, and $\mathrm{CdO}$ in rocksalt, cesium chloride, zinc blende, and wurtzite structure. In the case of $\mathrm{MgO}$ we also examine the nickel arsenide structure and a graphitic phase. The stability of the ground-state phases rocksalt $(\mathrm{MgO},\mathrm{CdO})$ and wurtzite $(\mathrm{ZnO})$ against hydrostatic pressure and biaxial strain is studied. We also present the band structures of all polymorphs as well as the accompanying dielectric functions. We discuss the physical reasons for the anomalous chemical trend of the ground-state geometry and the fundamental gap with the size of the group-II cation in the oxide. The role of the shallow $\mathrm{Zn}3d$ and $\mathrm{Cd}4d$ electrons is critically examined.

320 citations

Journal ArticleDOI
TL;DR: In this paper, Li et al. provided a fundamental understanding on the origin of the effective anchoring of LiPSs by N-doped carbon materials, which suppresses the shuttling of LiPss and produces significant improvement in the cycling performance of Li-S batteries.

320 citations

References
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Book
31 Dec 1993
TL;DR: The linearized augmented planewave (LAPW) method has emerged as the standard by which density functional calculations for transition metal and rare-earth containing materials are judged.
Abstract: With its extreme accuracy and reasonable computational efficiency, the linearized augmented planewave (LAPW) method has emerged as the standard by which density functional calculations for transition metal and rare-earth containing materials are judged. This volume presents a thorough and self-conta

1,150 citations