LibRPA: A software package for low-scaling first-principles calculations of random phase approximation electron correlation energy based on numerical atomic orbitals

LibRPA is a software package designed for efficient calculations of random phase approximation (RPA) electron correlation energies from first principles using numerical atomic orbital (NAOs). Leveraging a localized resolution of identity (LRI) technique, LibRPA achieves O(N^2) or better scaling behavior, making it suitable for large-scale calculation of periodic systems. Implemented in C++ and Python with MPI/OpenMP parallelism, LibRPA integrates seamlessly with NAO-based density functional theory (DFT) packages through flexible file-based and API-based interfaces. In this work, we present the theoretical framework, algorithm, software architecture, and installation and usage guide of LibRPA. Performance benchmarks, including the parallel efficiency with respect to the computational resources and the adsorption energy calculations for H20 molecules on graphene, demonstrate its nearly ideal scalability and numerical reliability. LibRPA offers a useful tool for RPA-based calculations for large-scale extended systems.LibRPA是一款专为基于第一性原理、利用数值原子轨道（numerical atomic orbitals，NAOs）高效计算随机相位近似（random phase approximation，RPA）电子关联能而开发的软件包。该软件借助局域化单位算符分解（localized resolution of identity，LRI）技术，实现了O(N²)及更优的计算标度行为，可适用于大规模周期性体系的量化计算。LibRPA采用C++与Python编写，并支持MPI/OpenMP并行计算，通过灵活的基于文件与基于应用程序编程接口（application programming interface，API）的两种接口方式，可与基于NAOs的密度泛函理论（density functional theory，DFT）软件包实现无缝集成。本工作详细介绍了LibRPA的理论框架、算法实现、软件架构，以及安装与使用指南。文中给出的性能基准测试结果，包括针对计算资源的并行效率测试与石墨烯表面H₂O分子的吸附能计算，验证了其近乎理想的可扩展性与数值可靠性。LibRPA为面向大规模扩展体系的基于RPA的量化计算提供了一款实用工具。