Electric displacement as the fundamental variable in electronic-structure calculations
Electric displacement as the fundamental variable in electronic-structure calculations
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DOI：
10.1038/nphys1185
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发表时间：
2009-04-01
期刊：
影响因子：
19.6
通讯作者：
Vanderbilt, David
中科院分区：
文献类型：
--
作者：
Stengel, Massimiliano;Spaldin, Nicola A.;Vanderbilt, David
周期性绝缘体中的电磁场计算在技术上和概念上都具有挑战性，这是由于在扩展固体中定义极化的基本问题。虽然最近已经取得了重大进展，建立了技术，以固定的电场E或宏观极化P的第一性原理计算，这两种方法缺乏易用性和概念清晰的标准零场计算。在这里，我们开发了一个新的形式主义，其中的电位移D，而不是E或P，是基本的电变量。固定D具有施加开路电边界条件的直观解释，这在研究铁电系统中特别有用。此外，类比开路电容器建议一个有吸引力的重新制定方面的自由电荷和电位，这大大简化了处理的应力和应变。以PbTiO（3）为例，我们表明，我们的技术能够完全控制密度泛函形式主义内的电变量。
Finite-field calculations in periodic insulators are technically and conceptually challenging, owing to fundamental problems in defining polarization in extended solids. Although significant progress has been made recently with the establishment of techniques to fix the electric field E or the macroscopic polarization P in first-principles calculations, both methods lack the ease of use and conceptual clarity of standard zero-field calculations. Here we develop a new formalism, in which the electric displacement D, rather than E or P, is the fundamental electrical variable. Fixing D has the intuitive interpretation of imposing open-circuit electrical boundary conditions, which is particularly useful in studying ferroelectric systems. Furthermore, the analogy to open-circuit capacitors suggests an appealing reformulation in terms of free charges and potentials, which dramatically simplifies the treatment of stresses and strains. Using PbTiO(3) as an example, we show that our technique enables full control over the electrical variables within the density functional formalism.