密度泛函理论
哈密顿量(控制论)
联轴节(管道)
物理
耦合常数
凝聚态物理
结晶学
材料科学
量子力学
化学
数学
数学优化
冶金
作者
Andreas Hermann,Brian Vest,Peter Schwerdtfeger
标识
DOI:10.1103/physrevb.74.224402
摘要
We present first-principles density functional calculations (DFT) on the $\ensuremath{\alpha}$ phase solid state of the transition metal dihalide compound $\mathrm{Cr}{\mathrm{Cl}}_{2}$. Structural parameters are optimized using local spin density approximation (LSDA) and semilocal generalized gradient approximation (GGA) exchange-correlation functionals. Different magnetic coupling schemes are investigated. In agreement with experiment we find that $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Cr}{\mathrm{Cl}}_{2}$ forms antiferromagnetically coupled chains that are connected via weaker Cr-Cl bonds. The internal crystal parameters are well described within DFT-GGA. The absorption spectrum near the onset is dominated by spin-allowed transitions between neighboring Cr atoms. Magnetic coupling constants are calculated from symmetry-breaking solutions of the electronic Hamiltonian. Several DFT-based methods are benchmarked with respect to their ability to reproduce the experimental coupling constants. Both LSDA and GGA fail to do so, and the inclusion of exact exchange worsens the results. Introducing a suitable onsite repulsion term yields good agreement with experiment.
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