### Abstract

We present an ab initio study of the excited state properties of silicon nanoparticles (NPs) with diameters of 1.2 and 1.6 nm. Quasiparticle corrections were computed within the G_{0}W_{0} approximation. The absorption spectra were computed by time-dependent density functional theory (TDDFT) using the adiabatic PBE approximation, and by solving the Bethe-Salpeter equation (BSE). In our calculations, we used recently developed methods that avoid the explicit inversion of the dielectric matrix and summations over empty electronic states. We found that a scissor operator reliably describes quasiparticle corrections for states in the low energy part of the spectra. Our results also showed good agreement between the positions of the absorption peaks obtained using TDDFT and the BSE in the low part of the spectra, although the peak intensities differ. We discuss the effect of the Tamm-Dancoff approximation on the optical properties of the NPs and present a quantitative analysis in terms of sum rules. In the case of the BSE we found that, even in the absence of the Tamm-Dancoff approximation, the f-sum rule is not fully satisfied due to an inconsistency between the approximations used for the BSE kernel and for the quasiparticle Hamiltonian.

Original language | English |
---|---|

Pages (from-to) | 3290-3298 |

Number of pages | 9 |

Journal | Journal of Chemical Theory and Computation |

Volume | 10 |

Issue number | 8 |

DOIs | |

Publication status | Published - Aug 12 2014 |

### Fingerprint

### ASJC Scopus subject areas

- Physical and Theoretical Chemistry
- Computer Science Applications

### Cite this

*Journal of Chemical Theory and Computation*,

*10*(8), 3290-3298. https://doi.org/10.1021/ct5000956

**Ab initio optoelectronic properties of silicon nanoparticles : Excitation energies, sum rules, and Tamm-Dancoff approximation.** / Rocca, Dario; Vörös, Márton; Gali, A.; Galli, Giulia.

Research output: Contribution to journal › Article

*Journal of Chemical Theory and Computation*, vol. 10, no. 8, pp. 3290-3298. https://doi.org/10.1021/ct5000956

}

TY - JOUR

T1 - Ab initio optoelectronic properties of silicon nanoparticles

T2 - Excitation energies, sum rules, and Tamm-Dancoff approximation

AU - Rocca, Dario

AU - Vörös, Márton

AU - Gali, A.

AU - Galli, Giulia

PY - 2014/8/12

Y1 - 2014/8/12

N2 - We present an ab initio study of the excited state properties of silicon nanoparticles (NPs) with diameters of 1.2 and 1.6 nm. Quasiparticle corrections were computed within the G0W0 approximation. The absorption spectra were computed by time-dependent density functional theory (TDDFT) using the adiabatic PBE approximation, and by solving the Bethe-Salpeter equation (BSE). In our calculations, we used recently developed methods that avoid the explicit inversion of the dielectric matrix and summations over empty electronic states. We found that a scissor operator reliably describes quasiparticle corrections for states in the low energy part of the spectra. Our results also showed good agreement between the positions of the absorption peaks obtained using TDDFT and the BSE in the low part of the spectra, although the peak intensities differ. We discuss the effect of the Tamm-Dancoff approximation on the optical properties of the NPs and present a quantitative analysis in terms of sum rules. In the case of the BSE we found that, even in the absence of the Tamm-Dancoff approximation, the f-sum rule is not fully satisfied due to an inconsistency between the approximations used for the BSE kernel and for the quasiparticle Hamiltonian.

AB - We present an ab initio study of the excited state properties of silicon nanoparticles (NPs) with diameters of 1.2 and 1.6 nm. Quasiparticle corrections were computed within the G0W0 approximation. The absorption spectra were computed by time-dependent density functional theory (TDDFT) using the adiabatic PBE approximation, and by solving the Bethe-Salpeter equation (BSE). In our calculations, we used recently developed methods that avoid the explicit inversion of the dielectric matrix and summations over empty electronic states. We found that a scissor operator reliably describes quasiparticle corrections for states in the low energy part of the spectra. Our results also showed good agreement between the positions of the absorption peaks obtained using TDDFT and the BSE in the low part of the spectra, although the peak intensities differ. We discuss the effect of the Tamm-Dancoff approximation on the optical properties of the NPs and present a quantitative analysis in terms of sum rules. In the case of the BSE we found that, even in the absence of the Tamm-Dancoff approximation, the f-sum rule is not fully satisfied due to an inconsistency between the approximations used for the BSE kernel and for the quasiparticle Hamiltonian.

UR - http://www.scopus.com/inward/record.url?scp=84906263758&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84906263758&partnerID=8YFLogxK

U2 - 10.1021/ct5000956

DO - 10.1021/ct5000956

M3 - Article

VL - 10

SP - 3290

EP - 3298

JO - Journal of Chemical Theory and Computation

JF - Journal of Chemical Theory and Computation

SN - 1549-9618

IS - 8

ER -