Dipartimento di Chimica IFM, Università di Torino, Via Pietro Giuria 7, 10125 Torino, Italy.
J Phys Condens Matter. 2010 Apr 14;22(14):146008. doi: 10.1088/0953-8984/22/14/146008. Epub 2010 Mar 25.
First-principles periodic calculations (with the B3LYP (Becke, three-parameter, Lee-Yang-Parr) hybrid functional, all-electron localized basis functions, and the CRYSTAL code) were coupled to a cluster expansion scheme in order to investigate the monoclinic β' phase of LiFeO(2), where a partially disordered Fe-Li distribution is observed within a rocksalt-type superstructure. By least-energy optimizing a limited number of ordered configurations, and employing a two-body truncated cluster expansion, the values J(1) = -0.06(2) and J(2) = -0.125(8) eV were obtained for the excess interaction energies J(i) = J(LiFe, i) - (J(LiLi, i) + J(FeFe, i))/2 corresponding to the first and second coordination spheres, respectively; negligible values were computed for third and further coordinations. The ordering phase transformation α−>β'−>γ was then addressed. Antiferromagnetic versus ferromagnetic ordering was taken into account too, and proved to lower the energy by -0.0577 eV/f.u. The corresponding cluster expansion coefficients J(i) = J(AFM, i) - J(FM, i) are J(1) = 0.007(2) and J(2) = -0.044(5) eV.
采用第一性原理周期性计算（B3LYP 混合泛函、全电子局域基函数和 CRYSTAL 代码）与团簇展开方案相结合，研究了 LiFeO(2)的单斜β'相，其中在岩盐型超结构中观察到部分无序的 Fe-Li 分布。通过对有限数量的有序构型进行最低能量优化，并采用二体截断团簇展开，得到了第一和第二配位球分别对应的超额相互作用能 J(i) = J(LiFe, i) - (J(LiLi, i) + J(FeFe, i))/2 的值 J(1) = -0.06(2) 和 J(2) = -0.125(8) eV；第三和进一步配位的计算值可忽略不计。然后解决了有序相变 α−>β'−>γ。还考虑了反铁磁与铁磁有序，证明其可使能量降低-0.0577 eV/f.u。相应的团簇展开系数 J(i) = J(AFM, i) - J(FM, i) 为 J(1) = 0.007(2) 和 J(2) = -0.044(5) eV。
