报告题目：Basis-error-free RPA correlation energies for atoms and molecules based on the Sternheimer equation

报告人：任新国 教授（中科院物理所）

报告时间：2024年10月15日 （星期二）上午10：20 – 10：50

报告摘要：

Correlated methods involving virtual orbitals show slow convergence with respect to the basis size and practical calculations based on such methods suffer from basis set incompleteness errors. Here we develop a numerical technique that allows one to obtain numerically precise random phase approximation（RPA）electron correlation energies, so far for atoms [1] and diatomic molecules, which are free of basis set incompleteness errors. The key idea behind this technique is to compute the Kohn-Sham density response function by solving the Sternheimer equations on dense 1- and 2-dimensional radial grids, enabling the convergence of the RPA correlation energies to arbitrary numerical precision.  This approach provides unambiguous reference results for those obtained with finite basis sets, allowing for assessing the reliability of the commonly used extrapolation scheme, as well as the errors introduced by frozen core approximation. It can also guide the development of more efficient and systematic atomic basis sets, in particular in the context of numerical atomic orbitals.[1] H. Peng, S. Yang, H. Jiang, H. Weng, and X. Ren, J. Chem. Theory Comput. 19, 7199 (2023).Correlated methods involving virtual orbitals show slow convergence with respect to the basis size and practical calculations based on such methods suffer from basis set incompleteness errors. Here we develop a numerical technique that allows one to obtain numerically precise random phase approximation（RPA）electron correlation energies, so far for atoms [1] and diatomic molecules, which are free of basis set incompleteness errors. The key idea behind this technique is to compute the Kohn-Sham density response function by solving the Sternheimer equations on dense 1- and 2-dimensional radial grids, enabling the convergence of the RPA correlation energies to arbitrary numerical precision.  This approach provides unambiguous reference results for those obtained with finite basis sets, allowing for assessing the reliability of the commonly used extrapolation scheme, as well as the errors introduced by frozen core approximation. It can also guide the development of more efficient and systematic atomic basis sets, in particular in the context of numerical atomic orbitals.

[1] H. Peng, S. Yang, H. Jiang, H. Weng, and X. Ren, J. Chem. Theory Comput. 19, 7199 (2023).

报告人简介：

任新国，中科院物理所特聘研究员。2006年于德国奥格斯堡大学获得博士学位。先后在在柏林弗里兹-哈伯研究所（2006-2012，博士后）和中国科学技术大学量子信息实验室（2013-2019，特任研究员）工作；2019年11月加入物理所。长期从事第一性原理电子结构方法的发展和程序开发。研究领域包括：（1）密度泛函理论，特别是基于无规相近似的先进交换关联泛函方法；（2）格林函数理论，特别是基于GW近似的激发态计算方法；（3）大型第一性原理计算软件的开发。