State Key Laboratory of Ferro and Piezoelectric Materials and Devices of Hubei Province, Faculty of Physics and Electronic Technology, Hubei University, Wuhan 430062, China.
J Chem Phys. 2013 Jul 28;139(4):044702. doi: 10.1063/1.4813500.
The ferroelectric mechanism of croconic acid in terms of the electronic structure and the molecular structure was studied by first principles using the density functional theory with the generalized gradient approximation. The spontaneous polarization (Ps) was simulated by the Berry phase method. It is found that the large polarization originates from charge transfer due to the strong "push-pull" effect of electron-releasing and -withdrawing groups along the hydrogen bond. According to the characteristics of polarization of croconic acid, we constructed a one-dimensional ferroelectric Hamiltonian model to describe the ferroelectric properties of croconic acid. Based on the Hamiltonian model, the thermal properties of the ferroelectricity of croconic acid were studied by Monte Carlo method. The simulated Curie temperature is 756 K, and the spontaneous polarization keeps well temperature range stability up to 400 K. These results are in good agreement with the experimental data.
采用基于密度泛函理论的广义梯度近似方法，从电子结构和分子结构两方面研究了克罗酸的铁电机制。采用Berry 相位法模拟了自发极化（Ps）。研究发现，大的极化源于沿氢键的电子供体和受体的强烈“推拉”效应引起的电荷转移。根据克罗酸的极化特性，我们构建了一个一维铁电场论模型来描述克罗酸的铁电性质。基于这个哈密顿模型，我们采用蒙特卡罗方法研究了克罗酸铁电的热特性。模拟得到的居里温度为 756 K，自发极化在 400 K 温度范围内保持良好的温度稳定性。这些结果与实验数据吻合较好。
