Ab-initio calculation of the vibrational modes of SiH4, H2SiO, Si10H16, and Si10H14O

TL;DR

This study uses ab-initio methods to analyze vibrational modes of silicon nanocrystals, identifying spectral features and displacement patterns, with a focus on hydrogenated and oxidized forms for understanding their vibrational properties.

Contribution

It provides detailed vibrational mode analysis of silicon nanocrystals, including large oxidized clusters, using density-functional perturbation theory, which is novel for these specific structures.

Findings

Identification of oxygen-related spectral features

Analysis of displacement patterns of vibrational modes

Comparison of bond lengths and frequencies with experimental data

Abstract

We have studied the normal modes of hydrogenated and oxidized silicon nanocrystals, namely SiH4 (silan), H2SiO (silanon), Si10H16 and Si10H14O. The small clusters (SiH4 and H2SiO) have been used for convergence tests and their bondlengths and frequencies have been compared with experimental and theoretical reference data. For the large clusters (Si10H16 and Si10H14O) we have investigated the vibrational density of states where we have identified the oxygen-related spectral features. The vibrational modes have been also analyzed with respect to the displacement patterns. The calculations have been carried out within the density-functional and density-functional perturbation theory using the local-density approximation.