赝势平面波计算铀及铀化合物结构研究

构建了铀的“Vanderbilt”型USPP,能够以相对较小的计算量完成铀金属结构全优化.计算验证表明,超软赝势平面波方法对于金属铀的计算结果与全电子计算结果接近,能正确反映对铀的低温下低对称结构特点.对简单的NaCl以及CaF2结构的铀氧化物、碳化物以及氮化物晶体参数的计算结果与实验值相差不到3%.对非整数计量比UO2+x(0

Pseudopotential Plane-wave Study of the Uranium Metals and Uranium Compound

Ultrasoft pseudopotential was generated for uranium and the plane waves pseudopotential formalism was used to study its crystal structures at zero temperature as a function of pressure. The alpha phases of uranium were fully relaxed. The zero-pressure zero-temperature equilibrium volumes and bulk moduli are consistent with previous calculations, and in excellent agreement with the experiment. This is also the case for cell parameters and pressure-induced phase transitions. In the calculation of NaCl and CaF_2 structure type of compound of uranium, the difference of theoretical lattice constant and the experimental value is less than 3%. For UO_(2+x) the trend of the lattice shinking with the x value increase is in accord with the experiment. For large U_2C_3 and U_2N_3 complex cells the difference of theoretical lattice constant and the experimental value is less than 3%, and the difference of coordination of atom is less than 5%.