Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006, China.
Phys Chem Chem Phys. 2013 Oct 7;15(37):15518-27. doi: 10.1039/c3cp52989d.
The non-orthogonal localized molecular orbital (NOLMO) is the most localized representation of electronic degrees of freedom. As such, NOLMOs are thus potentially the most efficient for linear-scaling calculations of electronic structures for large systems. However, direct ab initio calculations with NOLMO have not been fully implemented and widely used, partly because of the slow convergence issue in the optimization of NOLMO. Towards realizing the potential of NOLMO for large systems, we applied an energy minimum variational principle for carrying out ab initio self-consistent-field (SCF) calculations with NOLMOs. We developed an effective preconditioning approach using the diagonal part of the second order derivatives and show that the convergence of the energy optimization is significantly improved. The speed of convergence of the energy and density are comparable with that of the conventional SCF approach, thus paving the way for the optimization of NOLMO in linear scaling calculations for large systems.
非正交局域分子轨道（NOLMO）是电子自由度最局域的表示。因此，对于大型系统的电子结构的线性标度计算，NOLMO 是最有效的。然而，直接使用 NOLMO 的从头算计算尚未完全实现和广泛使用，部分原因是 NOLMO 的优化中的收敛缓慢问题。为了实现 NOLMO 在大型系统中的潜力，我们应用了能量最小变分原理来进行 NOLMO 的从头算自洽场（SCF）计算。我们开发了一种有效的预处理方法，使用二阶导数的对角部分，并表明能量优化的收敛性得到了显著提高。能量和密度的收敛速度与传统的 SCF 方法相当，从而为大型系统的线性标度计算中的 NOLMO 优化铺平了道路。
