Theoretical Predictions for the Equation of State of Metal Nickel at Extreme Conditions

The equation of state (EOS) of metal nickel is theoretically studied up to 3000 K and concurrently 500 GPa by a direct integral approach to the partition function. The theoretical results agree very well with previous hydrostatic experiments at room temperature, and at high temperatures, the deviation between our calculated pressures and the latest hydrostatic experiments up to 109 GPa is less than 3.5%, 4.1%, and 4.6 % at 1000, 2000, and 3000 K, respectively. These results indicate our predictions at extreme conditions should be reliable. Furthermore, a universal model with only two parameters is developed to produce analytical EOS for general solids at high temperatures.