论文标题
周期系统的假想时间依赖性密度功能理论
Imaginary-time time-dependent density functional theory for periodic systems
论文作者
论文摘要
假想时间依赖性的密度功能理论（IT-TDDFT）被提议作为在密度功能理论（DFT）中获得基态的另一种方法，该方法避免了自企业始终场（SCF）迭代方法遇到的某些困难。以前，IT-TDDFT应用于原子簇，在某些情况下，在SCF难以收敛的情况下，它被证明会收敛。在目前的工作中，我们通过修改量子意式浓缩软件包来实现{\ it周期系统}的IT-tddft繁殖，该软件包使用具有多个$ \ boldsymbol {k} $点的平面波基础，并具有非collinear和dft+U计算的选项。我们证明，使用多个$ \ boldsymbol {k} $点的IT-TDDFT繁殖实现对于DFT+U非连接计算以及具有超柔软伪电位的DFT+U计算是正确的。在除一种情况下，我们实施IT-TDDFT传播的所有情况都会收敛于确切的SCF能量（至由双重精度保证的十进制），在这种情况下，它比SCF融合了略低，这表明SCF难以到达Kohn-Sham基层状态的系统中是有用的替代方法。此外，我们证明，如果我们在不同的动能平面波中使用自适应大小的假想时间步长，可以实现快速的收敛。
Imaginary-time time-dependent Density functional theory (it-TDDFT) has been proposed as an alternative method for obtaining the ground state within density functional theory (DFT) which avoids some of the difficulties with convergence encountered by the self-consistent-field (SCF) iterative method. It-TDDFT was previously applied to clusters of atoms where it was demonstrated to converge in select cases where SCF had difficulty with convergence. In the present work we implement it-TDDFT propagation for {\it periodic systems} by modifying the Quantum ESPRESSO package, which uses a plane-wave basis with multiple $\boldsymbol{k}$ points, and has the options of non-collinear and DFT+U calculations using ultra-soft or norm-conserving pseudo potentials. We demonstrate that our implementation of it-TDDFT propagation with multiple $\boldsymbol{k}$ points is correct for DFT+U non-collinear calculations and for DFT+U calculations with ultra-soft pseudo potentials. Our implementation of it-TDDFT propagation converges to the exact SCF energy (up to the decimal guaranteed by double precision) in all but one case where it converged to a slightly lower value than SCF, suggesting a useful alternative for systems where SCF has difficulty to reach the Kohn-Sham ground state. In addition, we demonstrate that rapid convergence can be achieved if we use adaptive-size imaginary-time-steps for different kinetic-energy plane-waves.
