Properties of real metallic surfaces: Effects of density functional semilocality and van der Waals nonlocality

Abstract

We have computed the surface energies, work functions, and interlayer surface relaxations of clean (111), (110), and (100) surfaces of Al, Cu, Ru, Rh, Pd, Ag, Pt, and Au. Many of these metallic surfaces have technological or catalytic applications. We compare experimental reference values to those of a family of non-empirical semilocal density functionals from the basic local density approximation (LDA) to our most advanced, general-purpose meta-generalized gradient approximation, SCAN. The closest agreement within experimental uncertainty is achieved by the simplest density functional LDA, and by the most sophisticated general-purpose one, SCAN+rVV10. The long-range van der Waals interaction incorporated through rVV10 increases the surface energies by about 10%, and the work functions by about 3%. LDA works for metal surfaces through a stronger-than-usual error cancellation. The PBE generalized gradient approximation tends to underestimate both surface energies and work functions, yielding the least accurate results. Interlayer relaxations from different functionals are in reasonable agreement with one another, and usually with experiment.

Crystallographic orientation dependence of work function: carbon adsorption on Au surfaces

“…The WF of the clean surfaces are calculated to be 5.55 eV, 5.43 eV, and 5.60 eV for Au(100), Au(110), and Au(111), respectively. These values are in agreement with the previously reported LDA calculations [9,20,21]. As the top panel in Fig.…”

“…It has been shown that LDA DFT results more closely agree with experiment, because the LDA exchange energy contribution to the surface energy is overestimated, while the correlation contribution is significantly underestimated. These two errors nearly cancel each other [9]. For gold, the ultrasoft pseudopotential (USPP) was generated with the Rappe Rabe Kaxiras Joannopoulos (rrkjus) scheme with 11 valence electrons in a 5d 10 6s configuration.…”

Common surface structures of graphene and Au(111): The effect of rotational angle on adsorption and electronic properties

“…Our SCAN+rVV10 functional estimation of 5.45 eV for the clean gold surface is in good agreement with recent theoretical values. [83] The PBE functional, on the other hand, gives a value of 5.12 eV for Au(111). Graphene monolayer is estimated to have a work function of 4.58 eV and 4.48 eV with and without the vdW-corrections, respectively.…”

Flux density measurements for 32 pulsars in the 20 cm observing band

“…With complex telescope systems (such as FAST, in which the surface of the dish and the focus cabin position continuously moves during a tracking observation) and new ultra-wide-band, or wide field-of-view, receivers new calibration procedures are becoming necessary. Novel calibration methods such as switching calibration signals at extremely high rates (Li, private communication), injecting pseudo-random-noise sequences, or short duration pulses (Patra et al 2017 are all currently being explored and we look forward to comparing these methods with the traditional calibration procedures in the near future. (24)…”