Density-functional calculation for the tunnel ionization rate of hydrocarbon molecules

Otobe, Tomohito; Yabana, Kazuhiro*

The tunnel ionization rate under a static intense electric field is calculated for some hydrocarbon molecules, acetylene, ethylene and benzene, employing the ab-initio density functional theory. The ionization rate is found to reflect the properties of the highest occupied molecular orbital, in agreement with the description of the molecular Ammosov-Delone-Krainov theory. Many-electron correlation effects beyond a single-electron approximation are discussed. The screening effect on the ionization rate is quantitatively evaluated.