Extra‐atomic relaxation and X‐ray spectra of narrow‐band metals. I. Formalism

Abstract

Theresults of a numerical analysis of the effect of the hole potential on the form of the X-ray spectra of narrow band metals are given. The dependence of the spectra on the magnitude of conduction band filling as well as on the magnitude of intratomic interaction between conduction band electrons and the hole is investigated. It is shown that when the band is filled, the emission and absorption spectra vary from a form of the spectra, which occurs if the hole potential is engaged adiabatically, to a form where the interaction with the hole is not taken into account. I n the first case the spectra reflect the local impurity density, and in the second one the density of states of the unperturbed matrix. If the hole potential is strong enough, then the formation of a local level is possible. The most interesting consequence of this is the presence of two lines in core XPS. The systematic change is recorded of the intensities of these lines as the band is filled. The results of the investigation are drawn into a qualitative interpretation of the width of emission bands and of the shift of the inner lines of d-metals. Es werden Ergebnisse einer numerischen Analyse des Einflusses des Lochpotentials auf dieForm von Rontgenspektren von Schrnalbandrnetallen angegeben. Die Abhangigkeit der Spektren sowohl vom Wert der Leitungsbandbesetzung als auch von der GroDe der interatornaren Wechselwirkung zwischen Leitungsbandelektronen und Lochern wird untersucht. Es wird gezeigt, daD die Fiillung der Biinder die Emissions-und Absorptionsspektren sich von der Spektrenform, die dann auftritt, wenn das Lochpotential adiabatisch eingeht, in eine Form Bndert, wo Wechselwirkung mit dem Loch nicht beriicksichtigt wird. Im ersten Fall spiegeln die Spektren die lokale Storstellendichte, und im zweiten die Zustandsdichte der ungestorten Matrix wider. Wenn das Lochpotential stark genug ist, ist die Bildung eines lokalen Niveaus moglich. Die interessanteste Konsequep ist die Anwesenheit von zwei Linien in den Rumpf -Rontgenphotospektren. Die systematische Anderung der Intensitiiten dieser Linien, wenn das Band gefullt wird, wird aufgezeichnet. Die Ergebnisse der Untersuchung werden in eine qualitative Interpretation der Breite der Emissionsbanden und der Verschiebung der inneren Linien der d-Metalle einbezogen.

Specific many-electron effects in X-ray spectra of simple metals and graphene

“…In Refs. [8,9] a quantitative one-band scheme of the MND calculation was proposed. Only recently [10,11], the MND theory was successfully applied for the calculation of the X-ray absorption spectra of graphite, where the electronic structure obtained from density functional theory (DFT) calculations was used as an input.…”

“…[8][9][10][11]. Here ab initio calculations of the K-and L 2,3 -XEB of the simple metals, as well as K-XEB of carbon in graphene were carried out including the MND effect for the first time.…”

“…Following the notation of Refs. [8,10] and neglecting the core hole natural width, we write the expression for the XEB intensity within the MND theory in the form…”

Local time-correlation approach for calculations of x-ray spectra

“…[13][14][15] Nevertheless, edgesingularity effects are most important in metallic systems near threshold, and are typically suppressed due to lifetime and other broadening effects.…”

“…(41) of Ref. [13]. Here E = ǫ c + ω and ρ ′ 00 (E) is the local density of states at the absorption site 0 in the presence of a core-hole.…”