Molecular dynamics study on thermal properties of UO2

The linear thermal expansion coeffident, the compressibility, and the molar specific heat of UO 2 were studied by a molecular dynamics (MD) technique in the temperature range of 300-1600K. The Morse-type potential function added to the Busing-Ida type potential was used. The calculated linear thermal expansion coefficient was lower than almost all the values of experimental data, but is found to increase with temperature similar to the real uranium dioxide. The calculated compressibility was slightly higher than that of the experimental data, but increased with temperature rise. This means that the MD cell becomes soft by rising temperature similar to the real material. The calculated molar specific heat of UO 2 at the constant pressure agreed with those of the experimental data at high temperatures. This result indicates that the potential function used in the present study well describes the change in the internal energy of UO 2 with temperature. From these results, the molecular dynamics calculation is applicable to evaluate the thermal properties of UO 2 .