Gupta D C, Kulshrestha Subhra
Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior-474 011 (MP), India.
J Phys Condens Matter. 2009 Oct 28;21(43):436011. doi: 10.1088/0953-8984/21/43/436011. Epub 2009 Oct 8.
The magnetic, structural, elastic and electronic properties of Sm-chalcogenides in the stable [Formula: see text] and high pressure [Formula: see text] phase have been analyzed using an ab initio pseudo-potential method with a spin-polarized GGA based on exchange-correlation energy optimization, as implemented in SIESTA code. The magnetic phase stability has been determined from the total energy calculations in non-magnetic and magnetic phases, which clearly indicate that at ambient and high pressures, these compounds are ferromagnetically stable. Also, the Sm ion is described in both five and six localized f electrons. Under compression the Sm chalcogenides undergo a first-order transformation from Sm(2+) to a stable valence state (Sm(3+)) with delocalization of the 4f electrons into the 5d states of Sm followed by a structural transition from the B1 to the B2 phase. The structural properties namely, equilibrium lattice constant, bulk modulus, its pressure derivative, transition pressure and volume collapse agree well with the experimental results. We have also computed the electronic structure at different volumes.
采用基于交换关联能优化的自旋极化广义梯度近似（GGA）从头算赝势方法，利用SIESTA代码分析了稳定的[化学式：见原文]和高压[化学式：见原文]相中的钐硫族化合物的磁性、结构、弹性和电子性质。通过非磁性和磁性相的总能计算确定了磁相稳定性，结果清楚地表明，在常压和高压下，这些化合物是铁磁稳定的。此外，Sm离子在五个和六个局域f电子中都有描述。在压缩过程中，钐硫族化合物经历从Sm(2+)到稳定价态（Sm(3+)）的一级转变，4f电子离域到Sm的5d态，随后发生从B1相到B2相的结构转变。其结构性质，即平衡晶格常数、体模量、其压力导数、转变压力和体积塌缩与实验结果吻合良好。我们还计算了不同体积下的电子结构。
