Ab initio thermodynamics beyond the quasiharmonic approximation: W as a prototype

作者：Xiang, Shikai^*; Xi, Feng; Bi, Yan; Xu, Ji'an; Geng, Huayun; Cai, Lingcang; Jing, Fuqian

来源：Physical Review B, 2010, 81(1): 014301.

DOI：10.1103/PhysRevB.81.014301

• AUGMENTED-WAVE METHOD
• ENERGY CALCULATIONS
• HIGH-PRESSURES
• EXPANSION
• DYNAMICS
• CRYSTAL
• STATE
• IRON
• AL

We present a simple but accurate scheme to compute the thermodynamic properties of crystalline solids in a wide range of pressure and temperature based on ab initio calculations. Compared to the method based on ab initio thermodynamic-integration techniques, our approach can reduce dramatically the number of ab initio molecular-dynamics simulations needed in the calculations of the intrinsic anharmonic effect neglected in the conventional quasiharmonic approximation. Taking tungsten as an example, we show that its thermal properties including the linear thermal-expansion coefficient and the equation of state (EOS) at high pressures and temperatures can be calculated accurately. The precise EOS of W for the pressure up to 500 GPa and the temperature up to 10 000 K may serve as a pressure scale. This method may be able to be extended to the study of solid-solid phase transitions of various crystalline solids, including some alloys.

• 出版日期2010-1
• 单位中国工程物理研究院流体物理研究所