论文标题
从头开始的散装自由能表面适当的铁电。
Ab Initio bulk free energy surface of proper ferroelectrics
论文作者
论文摘要
我们报告了一种系统，准确的方法，用于从适当的铁电特性的第一原理密度功能理论（DFT）得出大量自由能（FES），这是温度，极化和应变的函数。我们方法的核心是元动力学算法，该算法从没有先验的ansatz的情况下提取了全原子分子动力学模拟中FE的极化依赖性。其余的FES源自跨越相关相位空间的元动力轨迹。在铅钛酸铅的情况下，我们证明了我们的方法。由于DFT数字，全原子分子动力学和通过增强采样的自由能评估，整个相变的误差可以系统地控制，并且阶的阶段为1MEV/ATOM。由此产生的AB始于FES的准确性仅受DFT的功能近似的限制。
We report a systematic and accurate approach for deriving the bulk free energy surface (FES), a function of temperature, polarization, and strain, from the first-principles density functional theory (DFT) of proper ferroelectrics. The core of our approach is the metadynamics algorithm that extracts the polarization dependence of the FES from all-atom molecular dynamics simulations without an a priori ansatz. The rest of the FES is derived from the metadynamics trajectories that span the relevant phase space. We demonstrate our approach in the case of lead titanate. The errors across the phase transition, due to DFT numerics, all-atom molecular dynamics, and free energy evaluation by enhanced sampling, can be systematically controlled and are of the order of 1meV/atom. The accuracy of the resulting ab initio FES is only limited by the adopted functional approximation of DFT.
