Journal of Computer Chemistry, Japan -International Edition Vol. 3(2017)

Adding a polarization function to a basis set for molecular orbital calculation is frequently useful for producing accurate representations of chemical bonding. This article explains practical training that could greatly promote intuitive understanding of the general idea of adding a 3d-type polarization function in a π-type molecular-orbital function. In the training, by using Microsoft Excel, students draw contour plots of the molecular orbitals supplemented with and without the polarization function in ethylene (CH₂ = CH₂), and visualize the effect of the addition.

Radioactive substances are diffused by meteorological effects and soil property or underground water. The movements affect the ambient dose rate slowly and with smoothing in the long term. We detect the phenomena at monitoring posts in Fukushima. The monitoring post measures the flux from radionuclides; therefore, we discuss relations between the flux and mass density. Time-decreasing of the flux is a function of convection-diffusion of carriers of the nuclides. At the same time, it is also a decay function of radionuclides. We discuss product of the two functions, and get an expression for the time series of radioactive contaminated grounds. By using the expressions, we research changes of typical contaminants in Fukushima. This indicates movements of radionuclides.