Accelerating excited-state calculations in NanoGW using an interpolative separable density fitting method

The NanoGW package implements some of the most widely used methods for calculating excited-state properties, including time-dependent density function theory (TDDFT), GW approximation, and Bethe-Salpeter equation in the single-particle orbital basis. Solving Casida’s equation of TDDFT and performing GW/BSE calculations with NanoGW involve the computation of many electron-repulsion integrals. We will discuss the implementation of the interpolative separable density fitting (ISDF) method, a new density-fitting method [1] with O(N_atom³) computational complexity, in NanoGW. With ISDF method, we can reduce the number of electron-repulsion integrals from O(N_atom⁴) to O(N_atom²).

[1] W. Hu, L. Lin, and C. Yang, J. Chem. Theory Comput. 2017, 13, 11, 5420-5431