Study of the terahertz spectra of crystalline materials using NDDO semi-empirical methods: polyethylene, poly(vinylidene fluoride) form II and $\alpha$-D-glucose

TL;DR

This study evaluates the effectiveness of NDDO semi-empirical quantum chemistry methods, specifically PM6 and PM7, in interpreting terahertz spectra of crystalline polyethylene, poly(vinylidene fluoride) form II, and $ ext{ extalpha}$-D-glucose, showing promising qualitative agreement.

Contribution

It demonstrates that NDDO semi-empirical methods can reliably interpret terahertz spectra of crystalline materials, offering a computationally efficient alternative to more intensive methods.

Findings

Good qualitative agreement with experimental spectra

PM6 and PM7 methods effectively interpret low-frequency vibrational modes

Potential for rapid spectral analysis of crystalline materials

Abstract

Semi-empirical quantum chemistry methods offer a very interesting compromise between accuracy and computational load. In order to assess the performance of NDDO methods in the interpretation of terahertz spectra, the low frequency vibration modes of three crystalline materials, namely, polyethylene, poly(vinylidene fluoride) form II and $\alpha$-D-glucose have been studied using the PM6 and PM7 Hamiltonians and the results have been compared with the experimental data and former calculations. The results show good qualitative or semi-quantitative agreement with the experimentally observed terahertz spectra.