A Study of the Terahertz Spectra of Crystalline Materials (Polyethylene, Poly(Vinylidene Fluoride) form II, and alpha-D-Glucose) Using NDDO Semiempirical Methods

Semiempirical quantum chemistry methods offer a very interesting compromise between accuracy and computational complexity. 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 in order to assess the performance of NDDO methods in the interpretation of terahertz spectra. The results have been compared with the available experimental data and former calculations performed using alternative methods. NDDO calculations are in good qualitative or semiquantitative agreement with the experimentally observed terahertz spectra.