作　　者： ; ; ; ;

机构地区： 宜宾学院

出　　处： 《原子与分子物理学报》 2013年第4期630-636,共7页

摘　　要： 基于准谐近似理论,运用第一性原理投影缀加波方法研究了Ir的热力学和弹性性质,得到Ir的声子谱、状态方程、热容、熵、焓和线膨胀系数,以及弹性常数、弹性模量、剪切模量和杨氏模量随温度的变化关系.结果表明,计算的Ir声子谱和有限的实验测量结果一致;考虑电子对体系自由能贡献后计算的热容、熵、焓和线膨胀系数与实验值符合较好;在2600K时,Ir的电子定压热容占总定压热容的17%,因此在高温时电子对Ir定压热容的贡献是不能忽略的;理论预测的Ir室温下的弹性常数、弹性模量、剪切模量、杨氏模量和实验值测量值基本吻合,并随温度的增加而逐渐减小. Within the framework of the quasiharmonic approximation,the thermodynamics and elastic properties,including phonon dispersion curves,equation of state,linear thermal expansion coefficient and temperature-dependent entropy,enthalpy,heat capacity,elastic constants,bulk modulus,shear modulus,Young’s modulus of Ir have been studied using first-principles projector-augmented wave method.The results revealed that the predicted phonon dispersion curves of Ir are in agreement with the experimental measurements by neutron diffractions.Considering the thermal electronic contribution to Helmholtz free energy,the calculated entropy,enthalpy,heat capacity and linear thermal expansion coefficient from the first-principle are consistent well with the experimental data.At 2600 K,the electronic heat capacity accounts for 17% of the total heat capacity at constant pressure,thus the thermal electronic contribution to Helmholtz free energy is very important.The predicted elastic constants,bulk modulus,shear modulus and Young’s modulus at room temperature are also in agreement with the available measurements and increase with the increasing temperature

关 键 词： 第一性原理 热力学 弹性性质

领　　域： [理学]