Quasiparticle band structures and lifetimes in noble metals using Gaussian orbital basis sets

10 páginas, 6 figuras, 4 tablas.-- PACS number(s): 71.15.Ap, 71.20.-b.-- et al.We present the calculations of quasiparticle bandstructures and lifetimes for noble metals Cu and Ag within the GW approximation based on localized Gaussian orbital basis sets. For Cu, both the calculated positions of the d bands and the width of the d bands are within 0.1 eV compared to the experimental results. For Ag, partial core correction should be included in the pseudopotential to get reliable positions of the d bands. The calculated lifetimes agree with the experiment in the energy region away from the Fermi level, but deviate from the experimental results near the Fermi level where short-range interactions which GW approach fails to describe play an important role. For a better description of the lifetime near the Fermi level, terms beyond the GW approximation in the many-body perturbation theory need to be considered.This work has been supported by the Niedersachsen Ph. D. program ”Synthesis and Characterization of Surfaces and Interfaces assembled from Clusters and Molecules” and by the Deutsche Forschungsgemeinschaft (Bonn, Germany) by Grant No. Ro 1318/4–3.Peer reviewe

Modification of a Shockley-Type Surface State on Pt(111) upon Deposition of Gold Thin Layers

We present a first-principles fully-relativistic study of surface and interface states in the n one monolayer (ML) Au/Pt(111) heterostructures. The modification of an unoccupied s - p -type surface state existing on a Pt(111) surface at the surface Brillouin zone center upon deposition of a few atomic Au layers is investigated. In particular, we find that the transformation process of such a surface state upon variation of the Au adlayer thickness crucially depends on the nature of the relevant quantum state in the adsorbate. When the Au adlayer consists of one or two monolayers and this relevant state has energy above the Pt(111) surface state position, the latter shifts downward upon approaching the Au adlayer. As a result, in the 1 ML Au/Pt(111) and 2 ML Au/Pt(111) heterostructures at the equilibrium adlayer position, the Pt-derived surface state experiences strong hybridization with the bulk electronic states and becomes a strong occupied resonance. In contrast, when the number n of atomic layers in the Au films increases to three or more, the Pt(111) surface state shifts upward upon reduction of the distance between the Pt(111) surface and the Au adlayer. At equilibrium, the Pt-derived surface state transforms into an unoccupied quantum-well state of the Au adlayer. This change is explained by the fact that the relevant electronic state in free-standing Au films with n ≥ 3 has lower energy in comparison to the Pt(111) surface state.3.9003.2017/$\Pi$220 or 3.9003.2017/9.10 Ministry of Education and Science of the Russian Federation Project No. 15.61.202.2015 Saint Petersburg State University IT-756-13 Euskal Herriko Unibertsitatea FIS2016-76617-P and FIS2016-75862-P Spanish Ministry of Economy, Industry and Competitiveness MINEIC

Screening in Graphene: Response to External Static Electric Field and an Image-Potential Problem

We present a detailed first-principles investigation of the response of a free-standing graphene sheet to an external perpendicular static electric field E. The charge density distribution in the vicinity of the graphene monolayer that is caused by E was determined using the pseudopotential density-functional theory approach. Different geometries were considered. The centroid of this extra density induced by an external electric field was determined as zim = 1.048 Å at vanishing E, and its dependence on E has been obtained. The thus determined zim was employed to construct the hybrid one-electron potential which generates a new set of energies for the image-potential states.V.M.S. acknowledges support from the Project of the Basque Government for consolidated groups of the Basque University, through the Department of Universities (Q-NANOFOT IT1164-19) and from the Spanish Ministry of Science and Innovation (Grant No. PID2019–105488GB–I00). G.G. would like to acknowledge the support from the Air Force Research Laboratory (AFRL) through Grant No. FA9453-21-1-0046

Effects of 5d electrons and spin-orbit interaction on the characteristics of bulk plasmons in lead

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).An ab initio study of the dynamical dielectric response of bulk lead is presented. The influence of the 5d semicore states on the characteristics of the bulk plasmon is analyzed by means of first-principles pseudopotential calculations. The effects of spin-orbit interactions and local-fields are also studied in detail. The inclusion of the 5d semicore states in the valence configuration completely changes the high-energy-transfer dielectric properties of bulk Pb. In particular, it lowers the computed bulk plasmon energy by about 3.5 eV, bringing its frequency to good agreement with experimental data. In general, the high-energy-transfer dielectric response of bulk Pb is found to be shaped mostly by the interplay between the interband transitions involving the semicore 5d states and the spin-orbit coupling interaction. Local-field effects are found to affect the relative spectral weight of the high-energy excitations, while leaving their dispersion mostly unaffected.We acknowledge financial support from the Spanish MINECO (Grant No. FIS2013-48286-C2-1-P), the Departamento de Educacion del Gobierno Vasco, and the University of the Basque Country (Grant No. GIC07-IT-366-07).Peer Reviewe

Unusual dispersion of image potential states on the Be(101¯0) surface

We present a self-consistent pseudopotential calculation of image potential states on the Be(101¯0) surface. The one-electron potential inside the crystal and surface region is described by the local density approximation and by the image potential in the vacuum region (at z>zim). The calculated first image state (E1=−1.20 eV) lies in the symmetry gap and the second image state (E2=−0.31 eV) is located inside the absolute energy gap. High anisotropy of the dispersion of both image states is found. The effective masses that reflect this anisotropy are obtained m*1/me=1.55±0.1, m*2/me=1.30±0.1 along the ¯Γ¯M direction and m*1/me=0.40±0.05, m*2/me=0.55±0.05 along ¯ΓĀ. The unusual dispersion of the image states on Be(101¯0) is due to a large penetration value pn of these states (p1=0.34 and p2=0.15), and the very anisotropic character of the symmetry energy gap edges.This project has been supported by the Ministerio de Educacion y Ciencia, Spain; the Departamento de Educacion del Gobierno Vasco; and Iberdrola S.A.Peer reviewe

Ab initio study of low-energy collective electronic excitations in bulk Pb

A theoretical study of the dynamical dielectric response of bulk lead at low energies is presented. The calculations are performed with full inclusion of the electronic band structure calculated by means of a first-principles pseudopotential approach. The effect of inclusion of the spin-orbit interaction in the band structure on the excitation spectra in Pb is analyzed, together with dynamical exchange-correlation and local-field effects. In general, results show significant anisotropy effects on the dielectric response of bulk Pb. At small momentum transfers along three different high-symmetry directions, the calculated excitation spectra present several peaks with strong acousticlike dispersion in the energy range below 2 eV. The analysis shows that only one of such modes existing at momentum transfers along the Γ-K direction can be interpreted as a true acousticlike plasmon, whereas all other modes are originated from the enhanced number of intraband electron-hole excitations at corresponding energies. Comparison with available optical experimental data shows good agreement. © 2013 American Physical Society.We acknowledge financial support from the Spanish MICINN (Grant No. FIS2010-19609-C02-01), the Departamento de Educación del Gobierno Vasco, and the University of the Basque Country (Grant No. GIC07-IT-366-07).Peer Reviewe

Acoustic Plasmons in Nickel and Its Modification upon Hydrogen Uptake

In this work, we study, in the framework of the ab initio linear-response time-dependent density functional theory, the low-energy collective electronic excitations with characteristic sound-like dispersion, called acoustic plasmons, in bulk ferromagnetic nickel. Since the respective spatial oscillations in slow and fast charge systems involve states with different spins, excitation of such plasmons in nickel should result in the spatial variations in the spin structure as well. We extend our study to NiHx with different hydrogen concentrations x. We vary the hydrogen concentration and trace variations in the acoustic plasmons properties. Finally, at x=1 the acoustic modes disappear in paramagnetic NiH. The explanation of such evolution is based on the changes in the population of different energy bands with hydrogen content variation.Y.M.K. acknowledges support from the Government research assignment for ISPMS SB RAS, project FWRW-2022-0001 (in the part of band structure calculations). I.V.S. acknowledges support from the Ministry of Education and Science of the Russian Federation within State Task No. FSWM-2020-0033 (in the part of electronic structure and dielectric function calculations). E.V.C. acknowledges support from Saint Petersburg State University (Project ID No. 90383050). V.M.S. acknowledges financial support by Grant No. PID2019-105488GB-I00 funded by MCIN/AEI/10.13039/501100011033/

Ultrafast electronic response of Ag(111) and Cu(111) surfaces: From early excitonic transients to saturated image potential

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).We investigate the evolution of attosecond to femtosecond screening and emergent potentials that govern the dynamics and energetics of electrons and holes excited in the various stages of multiphoton photoemission processes and control the photoelectron yield in recently reported experiments [X. Cui, C. Wang, A. Argondizzo, S. Garrett-Roe, B. Gumhalter, and H. Petek, Nat. Phys. 10, 505 (2014)1745-247310.1038/nphys2981]. The study is focused on the dynamical screening of holes created in preexistent quasi-two-dimensional Shockley state bands on Ag(111) and Cu(111) surfaces and of electrons excited to the intermediate and emerging screened states. Using the formalism of self-consistent electronic response, we analyze first the effects of screening on the dynamics of photoexcited electrons and holes and then of the Coulomb correlated photoexcited pair. Special attention is paid to the correlated primary electron-hole states, which commence as transient surface excitons and develop in the course of screening into uncorrelated electrons and holes propagating in the image potential and surface state bands, respectively. The obtained results enable to establish a consistent picture of transient electron dynamics at Ag(111) and Cu(111) surfaces that are becoming accessible by the time-, energy-, and momentum-resolved pump-probe multiphoton photoelectron spectroscopies.V.M.S. acknowledges partial support from the Basque Departamento de Educacion, UPV/EHU (Grant No. IT-756-13) and the Spanish Ministry od Economy and Competitiveness MINECO (Grant No. FIS2013-48286-C2-1-P). N.D. acknowledges the support of the Unity Through Knowledge Fund (UKF B1). H.P. was supported by the Division of Chemical Sciences, Geosciences and Biosciences, Office of Basic Energy Sciences of the U.S. Department of Energy through Grant DE-FG02-09ER 16056.Peer Reviewe

Acoustic plasmons in extrinsic free-standing graphene

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.An acoustic plasmon is predicted to occur, in addition to the conventional two-dimensional (2D) plasmon, as the collective motion of a system of two types of electronic carriers coexisting in the same 2D band of extrinsic (doped or gated) graphene. The origin of this novel mode stems from the anisotropy present in the graphene band structure near the Dirac points K and K'. This anisotropy allows for the coexistence of carriers moving with two distinct Fermi velocities along the γK and γK' directions, which leads to two modes of collective oscillation: one mode in which the two types of carriers oscillate in phase with one another (this is the conventional 2D graphene plasmon, which at long wavelengths (q → 0) has the same dispersion, q1/2, as the conventional 2D plasmon of a 2D free electron gas), and the other mode found here corresponds to a low-frequency acoustic oscillation (whose energy exhibits at long-wavelengths a linear dependence on the 2D wavenumber q) in which the two types of carriers oscillate out of phase. This prediction represents a realization of acoustic plasmons originated in the collective motion of a system of two types of carriers coexisting within the same band. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.MP acknowledges the financial support of MIUR (FIRB-Futuro in Ricerca 2010—Project PLASMOGRAPH grant no. RBFR10M5BT), the European Commission, the European Social Fund and Regione Calabria, (POR) Calabria—FSE 2007/2013. VMS acknowledges financial support from the Spanish MICINN (no. FIS2010-19609-C02-01), the Departamento de Educación del Gobierno Vasco, and the University of the Basque Country (no. GIC07-IT-366-07).Peer Reviewe

Dielectric screening and band-structure effects in low-energy photoemission

5 páginas, 3 figuras.-- PACS number(s): 79.60.-i, 73.20.MfNonlocal response of the surface to the incident light is included into an ab initio one-step photoemission theory. Surface-state normal emission spectra from Be(0001) and Al(100) are calculated by a full-potential scattering method and are found to agree well with the experiment in a wide energy range. The total exciting field is obtained within the random-phase approximation for jellium as well as for one-dimensional crystal models of the two surfaces. Material dependence of the multipole plasmon mode and strong effect of band structure on the photoyield is discussed.The authors acknowledge partial support from the University of the Basque Country Grant No. GIC07IT36607 and the Spanish Ministerio de Ciencia y Tecnología Grant No. FIS2007- 66711-C02-01 .Peer reviewe