Normal coordinate analysis and some other properties of various solids

Abstract

In part A, it is known that the carbon is vaporized to a mixture of molecular species such as $C_1$, $C_2$, $C_3$, and etc., and the larger polyatomic species become increasingly important effect on their thermodynamic properties at the higher temperature and pressure. Though little is presently known about the vapor species above $C_5$, in some estimate it is usually known that $C_3$ species are dominant at a relative condition. To make up for the lack in experimental data for liquid carbon, the thermodynamic properties of liquid carbon are calculated over a wide range of temperature from the triple point to critical point, by using the significant liquid structures model which has been successfully applied to many liquids. In part B, normal modes of solids HF, HCl, and polyethylene having the exciting spectrometric phenomena have been evaluated by taking the lowest temperature phase of these species in the solid. The solids HF and HCl have the same space group as $C_{2v}$, and polyethylene has a space group with $D_{2h}$. The normal modes were obtained by the valence force field with modified force constants and a quantitative description of the normal mode is adjusted by the potential energy distribution (PED). From the PED, the most fittable force constants are also obtained. We have intended to calculate the normal modes by using the smallest size of the model and the simple computational process. To remove the edge effects being occurred in constructing the single cluster model, different from the boundary condition being generally used up to now, the idea of pseudolattic method being successfully applied to M.O. calculations of solid was extended to normal mode analysis in order to give the same environment for all molecules in a chosen cluster. By using the above valence force field and boundary condition, we obtain the assigned frequencies and compare those results with the results obtained by others. In part C, normal modes of crystalline orthorhombic...