Computer simulation of structural modifications induced by highly energetic ions in uranium dioxide

Sasajima, Yasushi*; Osada, Takuya*; Ishikawa, Norito   ; Iwase, Akihiro*

The structural modification caused by the high-energy-ion irradiation of single-crystalline uranium dioxide was simulated by the molecular dynamics method. As the initial condition, high kinetic energy was supplied to the individual atoms within a cylindrical region of nanometer-order radius located in the center of the specimen. The potential proposed by Basak et al. was utilized to calculate interaction between atoms. The supplied kinetic energy was first spent to change the crystal structure into an amorphous one within a short period of about 0.3 ps, then it dissipated in the specimen. The amorphous track radius was determined as a function of the effective stopping power , i.e., the kinetic energy of atoms per unit length created by ion irradiation (: electronic stopping power, : energy transfer ratio from stopping power to lattice vibration energy).