ASM 2019

Poster (P68)


First principles electron-correlated calculations of linear optical absorption spectra in silicon hydrides: Si2H2n (n = 1 − 3)

 

Pritam Bhattacharyya, Deepak Kumar Rai, and Alok Shukla

 

Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India

 

We have performed first principles electron-correlated calculations employing large basis sets to optimize the geometries, and to compute linear optical absorption spectra of various low-lying conformers of sil- icon hydrides: Si2 H2n , n = 1, 2, 3. The geometry optimization for various isomers was carried out at the coupled-cluster singles-doubles and perturbative triples [CCSD(T)] level of theory, while their ex- cited states and absorption spectra were computed using a large-scale multi-reference singles-doubles configuration-interaction (MRSDCI) approach, which includes electron-correlation effects at a sophisti- cated level. Our calculated spectra are the first ones for Si2H2 and Si2H4 conformers, while for Si2H6 we obtain excellent agreement with the experimental measurements, suggesting that our computational approach is reliable. We also optimized some of the excited state geometries corresponding to a few fron- tier peaks of the optical spectra of all the isomers considered in this work. Our calculated absorption spectra exhibit a strong structure-property relationship, suggesting the possibility of identifying various conformers based on their optical absorption fingerprints. We also believe that our results will be useful for optical identification of hydrogenation induced defects in silicon thin films.

 

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