金红石、金红石、板钛矿和铌铁矿TiO $_2$多晶型物能量学的量子蒙特卡罗研究
Quantum Monte Carlo study of the energetics of the rutile, anatase, brookite, and columbite TiO$_2$ polymorphs
摘要：
采用扩散量子蒙特卡罗（DMC）方法和密度泛函理论（DFT）计算了TiO $_2$的低压金红石、金红石、板钛矿和高压铌铁矿的相对能量随温度的变化.振动能被发现是重要的规模上的利益和显着的四阶非谐性被发现在金红石相。静态晶格DFT计算预测，金红石的能量低于金红石，与实验不符。DMC计算提供的电子相关性的准确描述和非谐振动效应的列入有助于稳定金红石相对于金红石。我们的计算预测了在$630 \pm 210$ K下从金红石型到金红石型的$_2$的相变。
英文摘要：
The relative energies of the low-pressure rutile, anatase, and brookite polymorphs and the high-pressure columbite polymorph of TiO$_2$ have been calculated as a function of temperature using the diffusion quantum Monte Carlo (DMC) method and density functional theory (DFT). The vibrational energies are found to be important on the scale of interest and significant quartic anharmonicity is found in the rutile phase. Static-lattice DFT calculations predict that anatase is lower in energy than rutile, in disagreement with experiment. The accurate description of electronic correlations afforded by DMC calculations and the inclusion of anharmonic vibrational effects contribute to stabilizing rutile with respect to anatase. Our calculations predict a phase transition from anatase to rutile TiO$_2$ at $630 \pm 210$ K.
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