【摘要】 采用基于密度泛函理论的平面波赝势方法,计算了Fe的几种不同晶体结构的总能量曲线,对HCP结构下晶体结构参数c/a随压强的变化关系做计算分析.能量计算精度取为0.01eV/atom.计算得出:1)零温下Fe从bcc到hcp结构的相变压强约为15GPa,与实验结果相一致;2)压强的升高会导致Fe的磁矩减小,最终破坏Fe的磁性;3)压强升高引起hcp晶体结构参数c/a缓慢增大,而在地核压强(135—360GPa)范围内,c/a取常量约1.59能够满足计算精度的要求.更多还原

【Abstract】 In this paper,we performed first-principles calculations for iron with different crystal structures based on density-function theory,employing the pseudopotentional and plane-wave method.We set the computational precision of energy to 0.01 eV/atom and made total-energy calculations.The calculated results show that:1)The bcc iron undergoes a pressure-induced phase transform to hcp structure at about 15 GPa,which is in good-agreement with the experimental values;2)The magnetic moment decreases with increasing pressure,which demonstrates that the high pressures will destroy the magnetism of iron;3)The ratio of lattice parameters of hcp structure,c/a,will slowly increase with the pressure increasing.When set to a constant about 1.59,the c/a value can give the energy computation precision of 0.01 eV/atom under the pressures in the earth core.更多还原