@article{a471418b956f4a708937a02efef3140e,

title = "First principles local pseudopotential for silver: Towards orbital-free density-functional theory for transition metals",

abstract = "Orbital-free density-functional theory (OF-DFT) with modern kinetic-energy density functionals (KEDFs) is a linear scaling technique that accurately describes nearly-free-electron-like (main group) metals. In an attempt towards extending OF-DFT to transition metals, here we consider whether OF-DFT can be used effectively to study Ag, a metal with a localized d shell. OF-DFT has two approximations: use of a KEDF and local pseudopotentials (LPSs). This paper reports construction of a reasonably accurate LPS for Ag by means of inversion of the Kohn-Sham (KS) DFT equations in a bulk crystal environment. The accuracy of this LPS is determined within KS-DFT (where the exact noninteracting kinetic energy is employed) by comparing its predictions of bulk properties to those obtained from a conventional (orbital-based) nonlocal pseudopotential (NLPS). We find that the static bulk properties of fcc and hcp Ag predicted within KS-DFT using this LPS compare fairly well to those predicted by an NLPS. With the transferability of the LPS established, we then use this LPS in OF-DFT, where several approximate KEDFs were tested. We find that a combination of the Thomas-Fermi (TTF) and von Weizs{\"a}cker (TvW) functionals (TvW +0.4 TTF) produces better densities than those from the linear-response-based Wang-Teter KEDF. However, the equations of state obtained from both KEDFs in OF-DFT contain unacceptably large errors. The lack of accurate KEDFs remains the final barrier to extending OF-DFT to treat transition metals.",

author = "Baojing Zhou and Carter, {Emily A.}",

note = "Funding Information: We thank Professor Yan Alexander Wang (University of British Columbia) for providing the ALPS and Accelrys, Inc. for providing the CASTEP software. Financial support for this project was provided by the DOD-MURI program and the National Science Foundation. Table I. Comparison of various pseudopotential KS-LDA and experimental bulk properties for fcc and hcp Ag. Cohesive energies are not available using the BLPS (see Results of Sec. III for details); instead the equilibrium total energies per atom obtained from the Murnaghan fit are given in parentheses. V 0 ( {\AA} 3 ) B 0 ( GPa ) E c ( eV ∕ atom ) NLPS fcc 16.848 116 3.445 hcp 16.880 121 3.442 BLPS fcc 17.084 130 NA ( − 1221.080 ) hcp 17.610 143 NA ( − 1221.060 ) Other work a fcc 17.417 96 3.01 hcp 17.495 103 3.01 Experimental b fcc 16.817 101 2.95 a From Ref. 39 —KS-LDA/NLPS (HSC scheme). b From Ref. 41 . V 0 is extrapolated to 0 K, using the coefficient of thermal expansion for Ag (Ref. 42 ). FIG. 1. (a) The real space ALPS (dashed) and BLPS (solid) at short range; (b) Comparison of the ALPS (dashed), BLPS (solid), and NLPS (dot-dashed), including s , p , and d -channels, over longer range. The NLPS, ALPS, and BLPS are Coulombic beyond 7.43, 7.43, and 8.5 bohr, respectively. FIG. 2. KS-NLPS total energies ( eV ∕ atom ) vs atomic volume ( {\AA} 3 ) for fcc (dark squares) and hcp (open triangles) Ag. FIG. 3. Contour plot of KS-NLPS density. Dark areas represent high density, light areas low density. (a) (100) plane of fcc Ag; (b) (110) plane of hcp Ag. FIG. 4. The ALPS (dashed line), best BLPS (solid line), and form factors (symbols) of fcc (dark squares) and hcp (open circles) Ag obtained from the Wang–Parr method. (a) The full potential in reciprocal space [Eq. (9) ]. Inset: enlargement of intermediate g -vector region. (b) The corresponding quantities without Coulombic contributions [Eq. (10) ]. FIG. 5. KS-NLPS (solid) and KS-BLPS (dot-dashed) density slices (a) between the two nearest neighbors of fcc Ag and (b) between the two different atoms in the primitive unit cell for hcp Ag. FIG. 6. KS-LDA total energies ( eV ∕ atom ) vs atomic volume ( {\AA} 3 ) for (a) fcc Ag; (b) hcp Ag. Here we compare NLPS (solid diamonds) to BLPS (open circles) to ALPS (opaque triangles). The NLPS EOS is shifted down by 235.15 eV ∕ atom , while the ALPS EOS is shifted up by 232.733 eV ∕ atom . On this scale, only one data point is present for the ALPS. FIG. 7. LDA density slices between (a) nearest neighbors in fcc Ag and (b) the two different atoms in the primitive hcp cell. We compare KS (solid) to OF ∕ { T vW + 0.4 T TF } (dashed) to OF/WT KEDF (dot-dashed). FIG. 8. OF-BLPS total energies vs atomic volume for fcc Ag: T vW + 0.4 T TF (solid squares) vs WT KEDF (open circles). ",

year = "2005",

month = may,

day = "8",

doi = "10.1063/1.1897379",

language = "English (US)",

volume = "122",

journal = "Journal of Chemical Physics",

issn = "0021-9606",

publisher = "American Institute of Physics Publising LLC",

number = "18",

}