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arXiv 1702.04817cond-mat.mtrl-sci
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基于LDA、GGA和SCAN meta-GGA的原型铁电材料的第一性原理比较研究

Comparative first-principles studies of prototypical ferroelectric materials by LDA, GGA, and SCAN meta-GGA

Yubo Zhang, Jianwei Sun, John P. Perdew, Xifan Wu

摘要:

铁电性起源于破缺的空间反转对称性,是具有电偶极子的材料的功能性,其可以通过外部电场来切换。自发极化是一种重要的铁电性质,其幅度由极性结构畸变的强度决定。密度泛函理论(DFT)是研究铁电性质最常用的理论方法之一,但它受到电子交换关联近似水平的限制。一方面,局域密度近似(LDA)被认为是更准确的传统钙钛矿铁电体,如BaTiO 3和PbTiO 3比广义梯度近似(GGA),其中遭受所谓的超四边形误差。另一方面,GGA比LDA更适合于氢键铁电体,LDA在很大程度上高估了氢键的强度。在这里,我们表明,最近开发的通用强约束和适当规范(SCAN)元GGA功能显着改善了传统的LDA/GGA的结构,电气和能量特性的多样性结合的铁电材料具有可比的计算工作量,从而大大提高了DFT在铁电材料的研究中的预测能力。我们还解决了所观察到的系统依赖性能的LDA和GGA的铁电体从化学键的角度来看。

英文摘要:

Originating from a broken spatial inversion symmetry, ferroelectricity is a functionality of materials with an electric dipole that can be switched by external electric fields. Spontaneous polarization is a crucial ferroelectric property, and its amplitude is determined by the strength of polar structural distortions. Density functional theory (DFT) is one of the most widely used theoretical methods to study ferroelectric properties, yet it is limited by the levels of approximations in electron exchange-correlation. On the one hand, the local density approximation (LDA) is considered to be more accurate for the conventional perovskite ferroelectrics such as BaTiO3 and PbTiO3 than the generalized gradient approximation (GGA), which suffers from the so-called super-tetragonality error. On the other hand, GGA is more suitable for hydrogen-bonded ferroelectrics than LDA, which largely overestimates the strength of hydrogen bonding in general. We show here that the recently developed general-purpose strongly constrained and appropriately normed (SCAN) meta-GGA functional significantly improves over the traditional LDA/GGA for structural, electric, and energetic properties of diversely-bonded ferroelectric materials with a comparable computational effort, and thus enhances largely the predictive power of DFT in studies of ferroelectric materials. We also address the observed system-dependent performances of LDA and GGA for ferroelectrics from a chemical bonding point of view.

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