Ab-initio calculations of the quasi-particule and absorption spectra of clusters: the sodium tetramer
|Title||Ab-initio calculations of the quasi-particule and absorption spectra of clusters: the sodium tetramer|
|Publication Type||Palaiseau Article|
|Author Address|| |
ONIDA, G (Reprint Author), ECOLE POLYTECH,DECM,DTA,CEA,SOLIDES IRRADIES LAB,CNRS,URA 1380,F-91128 PALAISEAU,FRANCE. UNIV CAMBRIDGE,CAVENDISH LAB,CAMBRIDGE CB3 0HE,ENGLAND. UNIV ROMA TOR VERGATA,DIPARTIMENTO FIS,I-00173 ROME,ITALY. IBM CORP,DIV RES,ZURICH RES LAB,CH-8803 RUSCHLIKON,SWITZERLAND.
|Onida, G, Reining, L, Godby, RW, Del Sole, R, ANDREONI, W|
|Year of Publication||1995|
|Journal||Phys. Rev. Lett.|
We report the first ab initio quasiparticle calculation in a real cluster Na-4 within Hedin's GW approximation for the valence electron self-energy. Our approach avoids the summations over empty states, and also eliminates the problem of residual interactions between the periodic images. Self-energy corrections open the local density approximation gap by more than 2 eV; finite-size effects on screening are shown to play an important role. The absorption spectrum calculated by including excitonic effects using our ab initio screened interaction gives a good account of the experimental photodepletion data.