Shah Shikhar, Suryanarayana Phanish, Chow Edmond
School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30313, United States.
School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States.
J Chem Theory Comput. 2022 Jun 14;18(6):3474-3482. doi: 10.1021/acs.jctc.2c00166. Epub 2022 May 24.
In density functional theory, each self-consistent field (SCF) nonlinear step updates the discretized Kohn-Sham orbitals by solving a linear eigenvalue problem. The concept of pseudodiagonalization is to solve this linear eigenvalue problem approximately and specifically utilizing a method involving a small number of Jacobi rotations that takes advantage of the good initial guess to the solution given by the approximation to the orbitals from the previous SCF iteration. The approximate solution to the linear eigenvalue problem can be very rapid, particularly for those steps near SCF convergence. We adapt pseudodiagonalization to finite-temperature and metallic systems, where partially occupied orbitals must be individually resolved with some accuracy. We apply pseudodiagonalization to the subspace eigenvalue problem that arises in Chebyshev-filtered subspace iteration. In tests on metallic and other systems for a range of temperatures, we show that pseudodiagonalization achieves similar rates of SCF convergence to exact diagonalization.
在密度泛函理论中，每个自洽场（SCF）非线性步骤通过求解线性特征值问题来更新离散化的科恩-沙姆轨道。拟对角化的概念是近似求解这个线性特征值问题，具体来说是利用一种涉及少量雅可比旋转的方法，该方法利用了对上一次SCF迭代中轨道近似给出的解的良好初始猜测。线性特征值问题的近似解可以非常迅速，特别是对于接近SCF收敛的那些步骤。我们将拟对角化应用于有限温度和金属系统，在这些系统中，部分占据的轨道必须以一定精度单独求解。我们将拟对角化应用于切比雪夫滤波子空间迭代中出现的子空间特征值问题。在对一系列温度下的金属和其他系统进行的测试中，我们表明拟对角化实现了与精确对角化相似的SCF收敛速率。
