Transport and optical properties of CH2 plastics: Ab initio calculation and density-of-states-based analysis

This work covers an ab initio calculation of transport and optical properties of plastics of the effective composition CH2 at density 0.954 g cm3 in the temperature range from 5 kK up to 100 kK. The calculation is based on the quantum molecular dynamics, density functional theory and the Kubo-Greenwood formula. The temperature dependence of the static electrical conductivity σ1DC (T) has an unusual shape: σ1DC(T) grows rapidly for 5 kK ≤ T ≤ 10 kK and is almost constant for 20 kK ≤ T ≤ 60 kK. The additional analysis based on the investigation of the electron density of states (DOS) was performed. The rapid growth of σ1DC(T) at 5 kK ≤ T ≤ 10 kK is connected with the increase of DOS at the electron energy equal to the chemical potential ɛ = μ. The frequency dependence of the dynamic electrical conductivity σ1(ω) at 5 kK has the distinct non-Drude shape with the peak at ω 10 eV. This behavior of σ1(ω) was explained by the dip at the electron DOS.